drm/amdkfd: fix circular locking on get_wave_state

drm/amdkfd: fix circular locking on get_wave_state

[ Upstream commit 63f6e01237257e7226efc5087f3f0b525d320f54 ]

get_wave_state acquires the mmap_lock on copy_to_user but so do
mmu_notifiers.  mmu_notifiers allows dqm locking so do get_wave_state
outside the dqm_lock to prevent circular locking.

v2: squash in unused variable removal.

Signed-off-by: Jonathan Kim <jonathan.kim@amd.com>
Reviewed-by: Felix Kuehling <felix.kuehling@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>