drm/amdgpu/dce11: Re-set VBLANK interrupt state when enabling a CRTC
drm/amdgpu/dce11: Re-set VBLANK interrupt state when enabling a CRTC

Something (ATOM BIOS?) seems to be clobbering the LB_INTERRUPT_MASK
register while the CRTC is off, which caused e.g. glxgears or
gnome-shell to hang after a modeset.

Reviewed-and-Tested-by: Alex Deucher <08dc22c6156113f2deff178e35e3ed9b24d6af9e@amd.com>
Tested-by: Sonny Jiang <ce8b2206d1c203aef6ffc5d8886b3d2e0f59a252@amd.com>
Signed-off-by: Michel Dänzer <242b79f0804cf52679d58f27ed754158c1323c75@amd.com>

KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs