drm/i915/guc: Make intel_guc_recv static.

This function is only used by intel_guc_send() and it doesn't
need to be exposed outside of intel_uc.o file. Also when defined
as static, compiler will generate smaller code. Additionally let
it take guc param instead dev_priv to match function name.

Signed-off-by: Michal Wajdeczko <michal.wajdeczko@intel.com>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: Arkadiusz Hiler <arkadiusz.hiler@intel.com>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20161220115531.76120-1-michal.wajdeczko@intel.com