[Why]
IGT expects that pageflips can be triggered with the same
framebuffer before and after the commit

[How]
Expand the definition of pageflip to include any change
with an old framebuffer and a new framebuffer, even if they're
the same
Signed-off-by: NDavid Francis <David.Francis@amd.com>
Reviewed-by: NNicholas Kazlauskas <Nicholas.Kazlauskas@amd.com>
Acked-by: NBhawanpreet Lakha <Bhawanpreet.Lakha@amd.com>
Signed-off-by: NAlex Deucher <alexander.deucher@amd.com>