When recovery thread has begun GPU reset, there should be not other
threads to access hardware, otherwise system randomly hang.

v2 (chk): rewritten from scratch, use trylock and lockdep instead of
hand wiring the logic.

v3: add in_irq check

v4: change to check in_task
Signed-off-by: Dennis Li <Dennis.Li@amd.com>
Signed-off-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Hawking Zhang <Hawking.Zhang@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>