mali_kbase: backend: Ensure hard/soft-stop of jobs are not ignored

This commit fixes an issue where process termination with active GPU
work can be exploited to cause DoS attacks. This change will ensure
hard-stop request for all jobs in a context, e.g. during context
termination, is not ignored for relevant job regardless of its
priority. Also this this will do the same for soft-stops of all jobs
across all contexts e.g. when preparing a GPU reset.

ArmRef: GPUSWERRATA-1177
Provenance: https://collaborate.code.arm.com/#/c/3331/1


Bug: 197507971
Signed-off-by: Sidath Senanayake <sidaths@google.com>
Change-Id: Icb98e89407363a3676605514b7bb67c161397998
(cherry picked from commit 43772362d1cf6e1dc8411bf18c9dd9536eb8f4e2)