drm/scheduler: fix setting the priorty for entities (v2)

Since we now deal with multiple rq we need to update all of them, not
just the current one.

v2: Trivial: Removed unused variable (Alex)

Signed-off-by: Christian König <christian.koenig@amd.com>
Acked-by: Nayan Deshmukh <nayan26deshmukh@gmail.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>