drm/i915/gvt: Use offsetofend() rather than offsetof + sizeof

Compute the offset of the end of the crc32 field using offsetofend()
rather than open-coding.
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Zhenyu Wang <zhenyuw@linux.intel.com>
Cc: Zhi Wang <zhi.a.wang@intel.com>
Reviewed-by: Mika Kuoppala <mika.kuoppala@intel.com>
Signed-off-by: Zhenyu Wang <zhenyuw@linux.intel.com>

drivers/gpu/drm/i915/gvt/firmware.c

@@ -162,7 +162,7 @@ static int verify_firmware(struct intel_gvt *gvt,
 
 	h = (struct gvt_firmware_header *)fw->data;
 
-	crc32_start = offsetof(struct gvt_firmware_header, crc32) + 4;
+	crc32_start = offsetofend(struct gvt_firmware_header, crc32);
 	mem = fw->data + crc32_start;
 
 #define VERIFY(s, a, b) do { \