drm/xe/guc: Fail immediately on GuC load error

drm/xe/guc: Fail immediately on GuC load error

By using the same variable for both the return of poll_timeout_us and
the return of the polled function guc_wait_ucode, the return value of
the latter is overwritten and lost after exiting the polling loop. Since
guc_wait_ucode returns -1 on GuC load failure, we lose that information
and always continue as if the GuC had been loaded correctly.

This is fixed by simply using 2 separate variables.

Fixes: a4916b4da448 ("drm/xe/guc: Refactor GuC load to use poll_timeout_us()")
Signed-off-by: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
Reviewed-by: Matthew Brost <matthew.brost@intel.com>
Signed-off-by: Vinay Belgaumkar <vinay.belgaumkar@intel.com>
Link: https://patch.msgid.link/20260303001732.2540493-2-daniele.ceraolospurio@intel.com
(cherry picked from commit c85ec5c5753a46b5c2aea1292536487be9470ffe)
Signed-off-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>