drm/i915/skl: fix semicolon.cocci warnings

drivers/gpu/drm/i915/intel_pm.c:2913:4-5: Unneeded semicolon

 Removes unneeded semicolon.

Generated by: scripts/coccinelle/misc/semicolon.cocci

CC: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Signed-off-by: Fengguang Wu <fengguang.wu@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>