drm/amd: Make fence wait in suballocator uninterruptible

Commit c103a23f


("drm/amd: Convert amdgpu to use suballocation helper.")
made the fence wait in amdgpu_sa_bo_new() interruptible but there is no
code to handle an interrupt. This caused the kernel to randomly explode
in high-VRAM-pressure situations so make it uninterruptible again.

Signed-off-by: Simon Pilkington <simonp.git@gmail.com>
Fixes: c103a23f

 ("drm/amd: Convert amdgpu to use suballocation helper.")
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Christian König <christian.koenig@amd.com>
Link: https://gitlab.freedesktop.org/drm/amd/-/issues/2761
CC: stable@vger.kernel.org # 6.4+