drm/amd/display: Move disable interrupt into commit tail

[Why&How]
Since there is no need for accessing crtc state in the interrupt
handler, interrupts need not be disabled well in advance, and
can be moved to commit_tail where it should be.

Reviewed-by: Nicholas Kazlauskas <nicholas.kazlauskas@amd.com>
Signed-off-by: Aurabindo Pillai <aurabindo.pillai@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>