drm/xe/pxp: Remove incorrect handling of impossible state during suspend

drm/xe/pxp: Remove incorrect handling of impossible state during suspend

The default case of the PXP suspend switch is incorrectly exiting
without releasing the lock. However, this case is impossible to hit
because we're switching on an enum and all the valid enum values have
their own cases. Therefore, we can just get rid of the default case
and rely on the compiler to warn us if a new enum value is added and
we forget to add it to the switch.

Fixes: 51462211f4a9 ("drm/xe/pxp: add PXP PM support")
Signed-off-by: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
Cc: Alan Previn Teres Alexis <alan.previn.teres.alexis@intel.com>
Cc: Julia Filipchuk <julia.filipchuk@intel.com>
Reviewed-by: Julia Filipchuk <julia.filipchuk@intel.com>
Link: https://patch.msgid.link/20260324153718.3155504-8-daniele.ceraolospurio@intel.com