drm/xe: Fix xe_pm_runtime_get_if_active return

drm/xe: Fix xe_pm_runtime_get_if_active return

Current callers of this function are already taking the result
to a boolean and using in an if. It might be a problem because
current function might return negative error codes on failure,
without increasing the reference counter.

In this scenario we could end up with extra 'put' call ending
in unbalanced scenarios.

Let's fix it, while aligning with the current xe_pm_get_if_in_use
style.

Tested-by: Francois Dugast <francois.dugast@intel.com>
Reviewed-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240522170105.327472-1-rodrigo.vivi@intel.com
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>