drm/xe/tests/mocs: Update xe_force_wake_get() return handling

drm/xe/tests/mocs: Update xe_force_wake_get() return handling

With xe_force_wake_get() now returning the refcount-incremented domain
mask, a return value of 0 indicates failure for single domains.
Change assert condition to incorporate this change in return and
pass the return value to xe_force_wake_put()

v3
- return xe_wakeref_t instead of int in xe_force_wake_get()

v5
- return unsigned int for xe_force_wake_get()

Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Cc: Lucas De Marchi <lucas.demarchi@intel.com>
Signed-off-by: Himal Prasad Ghimiray <himal.prasad.ghimiray@intel.com>
Reviewed-by: Nirmoy Das <nirmoy.das@intel.com>
Reviewed-by: Badal Nilawar <badal.nilawar@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20241014075601.2324382-13-himal.prasad.ghimiray@intel.com
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>