[kernel][timer] clean up debug, return proper preemption, workaround compiler 'feature'
[kernel][timer] clean up debug, return proper preemption, workaround compiler 'feature'

minglun-tsai/lk,nvll/lk,hollanderic/lkstuff,ianloic/lk,M1cha/lk,travisg/lk,M1cha/lk,M1cha/lk,minglun-tsai/lk,pablomarx/lk,ErikCorryGoogle/lk,sndnvaps/lk,hollanderic/lkstuff,skabet/lk,pablomarx/lk,grub4android/lk,nvll/lk,skabet/lk,skabet/lk,srodrig1/lk,sndnvaps/lk,grub4android/lk,littlekernel/lk,srodrig1/lk,travisg/lk,pablomarx/lk,minglun-tsai/lk,travisg/lk,ErikCorryGoogle/lk,ErikCorryGoogle/lk,srodrig1/lk,srodrig1/lk,littlekernel/lk,srodrig1/lk,grub4android/lk,ErikCorryGoogle/lk,minglun-tsai/lk,ianloic/lk,sndnvaps/lk,skabet/lk,nvll/lk,pablomarx/lk,nvll/lk,GCrean/lk,ianloic/lk,grub4android/lk,littlekernel/lk,hollanderic/lkstuff,travisg/lk,sndnvaps/lk,nvll/lk,GCrean/lk,GCrean/lk,pablomarx/lk,littlekernel/lk,M1cha/lk,M1cha/lk,ianloic/lk,GCrean/lk,grub4android/lk,skabet/lk,GCrean/lk,sndnvaps/lk,hollanderic/lkstuff