drm/radeon: unpin cursor BOs on suspend and pin them again on resume (v2)

drm/radeon: unpin cursor BOs on suspend and pin them again on resume (v2)

Everything is evicted from VRAM before suspend, so we need to make
sure all BOs are unpinned and re-pinned after resume. Fixes broken
mouse cursor after resume introduced by commit 5c48f0a5.

[Michel Dänzer: Add pinning BOs on resume]

v2:
[Alex Deucher: merge cursor unpin into fb unpin loop]

Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=100541
Cc: stable@vger.kernel.org
Reviewed-by: Christian König <christian.koenig@amd.com> (v1)
Signed-off-by: Grigori Goronzy <greg@chown.ath.cx>
Signed-off-by: Michel Dänzer <michel.daenzer@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>