Revert "is spin lock really needed? removed for testing."

This reverts commit cbabaa6045d63ebdcd8246932f3b481f807933d6.
Revert "implement fb_sync instead of call sync manually."

This reverts commit f519840a14ed7c305f18ac13c435e86d79de68e3.
save irq when locking
sm712fb_accel.c: reinit the graphics engine.
Revert "save irq when locking"

This reverts commit b11f3395bcb73b79d66b053ce58f3753b391c47f.

Conflicts:
	sm712fb/sm712fb_accel.c
remove all locks
sm712fb_accel: refactor code
sm712fb_accel: refactor more code
sm712fb_accel.c: add comments.