drm/amdgpu: Add enforce_isolation sysfs attribute

This commit adds a new sysfs attribute 'enforce_isolation' to control
the 'enforce_isolation' setting per GPU. The attribute can be read and
written, and accepts values 0 (disabled) and 1 (enabled).

When 'enforce_isolation' is enabled, reserved VMIDs are allocated for
each ring. When it's disabled, the reserved VMIDs are freed.

The set function locks a mutex before changing the 'enforce_isolation'
flag and the VMIDs, and unlocks it afterwards. This ensures that these
operations are atomic and prevents race conditions and other concurrency
issues.

Cc: Christian König <christian.koenig@amd.com>
Cc: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Srinivasan Shanmugam <srinivasan.shanmugam@amd.com>
Suggested-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>