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 b9729b17.

[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>