drm/i915/guc: Fix sleep under spinlock during reset

drm/i915/guc: Fix sleep under spinlock during reset

Looks like intel_guc_reset had the ability to sleep under the
uncore spinlock since forever but it wasn't detected until the
recent changes annotated the wait for register with might_sleep.

I have fixed it by removing holding of the uncore spinlock over
the call to gen6_hw_domain_reset, since I do not see that is
really needed. But there is always a possibility I am missing
some nasty detail so please double check.

Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Michal Wajdeczko <michal.wajdeczko@intel.com>
Cc: Arkadiusz Hiler <arkadiusz.hiler@intel.com>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: Oscar Mateo <oscar.mateo@intel.com>
Acked-by: Michel Thierry <michel.thierry@intel.com>
Reviewed-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>