drm/xe: Simplify final return from xe_irq_install()

At the end of the function, we will always return err no matter it's
value. Simplify this by just returning the result of
drmm_add_action_or_reset().

Reviewed-by: Matt Roper <matthew.d.roper@intel.com>
Link: https://lore.kernel.org/r/20230915220233.59736-1-gustavo.sousa@intel.com


Signed-off-by: Gustavo Sousa <gustavo.sousa@intel.com>