MFC r273178: Update vt(4) for UEFI defaults and special keys
MFC r273178: Update vt(4) for UEFI defaults and special keys

  vt(4) is the default console for UEFI boot [1], and the bitmapped
  kern.vt.spclkeys sysctl has been replaced with individual kern.vt.kbd_*
  enable sysctls.

PR:		193710

jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase