The same function was duplicated in all the gfx IPs. Use
a single implementation for all.

v2: use static inline (Alex Xie)
Reviewed-by: NAlex Xie <AlexBin.Xie@amd.com>
Suggested-by: NAndres Rodriguez <andresx7@gmail.com>
Signed-off-by: NAlex Deucher <alexander.deucher@amd.com>