Fix serialization when a tx interrupt isn't scheduled
Fix serialization when a tx interrupt isn't scheduled

dev/uart.cc:
    Fix serialization when a tx interrupt isn't scheduled.

--HG--
extra : convert_revision : 3029e284cbba417e3f453d83fdf2ef307d684916

samueldotj/TeeRISC-Simulator,briancoutinho0905/2dsampling,markoshorro/gem5,briancoutinho0905/2dsampling,sobercoder/gem5,cancro7/gem5,SanchayanMaity/gem5,rallylee/gem5,qizenguf/MLC-STT,cancro7/gem5,powerjg/gem5-ci-test,zlfben/gem5,aclifton/cpeg853-gem5,zlfben/gem5,austinharris/gem5-riscv,KuroeKurose/gem5,qizenguf/MLC-STT,KuroeKurose/gem5,yb-kim/gemV,qizenguf/MLC-STT,kaiyuanl/gem5,rjschof/gem5,rjschof/gem5,yb-kim/gemV,sobercoder/gem5,TUD-OS/gem5-dtu,gem5/gem5,gedare/gem5,yb-kim/gemV,austinharris/gem5-riscv,rallylee/gem5,HwisooSo/gemV-update,kaiyuanl/gem5,rallylee/gem5,SanchayanMaity/gem5,rjschof/gem5,markoshorro/gem5,KuroeKurose/gem5,sobercoder/gem5,zlfben/gem5,cancro7/gem5,gem5/gem5,kaiyuanl/gem5,briancoutinho0905/2dsampling,rallylee/gem5,rjschof/gem5,kaiyuanl/gem5,zlfben/gem5,joerocklin/gem5,joerocklin/gem5,yb-kim/gemV,joerocklin/gem5,aclifton/cpeg853-gem5,briancoutinho0905/2dsampling,gem5/gem5,powerjg/gem5-ci-test,samueldotj/TeeRISC-Simulator,Weil0ng/gem5,Weil0ng/gem5,rallylee/gem5,samueldotj/TeeRISC-Simulator,samueldotj/TeeRISC-Simulator,joerocklin/gem5,aclifton/cpeg853-gem5,yb-kim/gemV,sobercoder/gem5,SanchayanMaity/gem5,qizenguf/MLC-STT,gem5/gem5,joerocklin/gem5,powerjg/gem5-ci-test,Weil0ng/gem5,austinharris/gem5-riscv,qizenguf/MLC-STT,Weil0ng/gem5,markoshorro/gem5,samueldotj/TeeRISC-Simulator,aclifton/cpeg853-gem5,cancro7/gem5,SanchayanMaity/gem5,TUD-OS/gem5-dtu,TUD-OS/gem5-dtu,gedare/gem5,cancro7/gem5,gedare/gem5,HwisooSo/gemV-update,rjschof/gem5,KuroeKurose/gem5,briancoutinho0905/2dsampling,zlfben/gem5,KuroeKurose/gem5,markoshorro/gem5,SanchayanMaity/gem5,HwisooSo/gemV-update,zlfben/gem5,TUD-OS/gem5-dtu,austinharris/gem5-riscv,austinharris/gem5-riscv,markoshorro/gem5,HwisooSo/gemV-update,HwisooSo/gemV-update,aclifton/cpeg853-gem5,gedare/gem5,gedare/gem5,rallylee/gem5,Weil0ng/gem5,KuroeKurose/gem5,qizenguf/MLC-STT,cancro7/gem5,Weil0ng/gem5,markoshorro/gem5,gem5/gem5,yb-kim/gemV,zlfben/gem5,SanchayanMaity/gem5,Weil0ng/gem5,gedare/gem5,kaiyuanl/gem5,HwisooSo/gemV-update,kaiyuanl/gem5,TUD-OS/gem5-dtu,powerjg/gem5-ci-test,yb-kim/gemV,rjschof/gem5,TUD-OS/gem5-dtu,powerjg/gem5-ci-test,aclifton/cpeg853-gem5,sobercoder/gem5,SanchayanMaity/gem5,gedare/gem5,briancoutinho0905/2dsampling,austinharris/gem5-riscv,austinharris/gem5-riscv,TUD-OS/gem5-dtu,joerocklin/gem5,yb-kim/gemV,samueldotj/TeeRISC-Simulator,aclifton/cpeg853-gem5,joerocklin/gem5,samueldotj/TeeRISC-Simulator,markoshorro/gem5,gem5/gem5,HwisooSo/gemV-update,cancro7/gem5,rjschof/gem5,briancoutinho0905/2dsampling,powerjg/gem5-ci-test,powerjg/gem5-ci-test,gem5/gem5,rallylee/gem5,kaiyuanl/gem5,sobercoder/gem5,sobercoder/gem5,KuroeKurose/gem5,qizenguf/MLC-STT,joerocklin/gem5