present: Don't check pixmap pitch in check_flip with non-DC >= 3.34

The current non-DC kernel driver also handles flipping between different
pitches correctly.

Reviewed-by: Nicholas Kazlauskas <nicholas.kazlauskas@amd.com>
12 jobs for amdgpu_present_check_flip-pitch-non-DC in 7 minutes and 6 seconds (queued for 1 minute and 5 seconds)