drm/panthor: Use the BITS_PER_LONG macro

sizeof(unsigned long) * 8 is the number of bits in an unsigned long
variable, replace it with BITS_PER_LONG macro to make them simpler.

And fix the warning:
WARNING: Comparisons should place the constant on the right side of the test
#23: FILE: drivers/gpu/drm/panthor/panthor_mmu.c:2696:
+ if (BITS_PER_LONG < va_bits) {

Signed-off-by: Jinjie Ruan <[e-mail]>
Reviewed-by: Steven Price <[e-mail]>
Signed-off-by: Steven Price <[e-mail]>
Link: https://patchwork.freedesktop.org/patch/msgid/[e-mail]

drivers/gpu/drm/panthor/panthor_mmu.c

···
 	 * which passes iova as an unsigned long. Patch the mmu_features to reflect this
 	 * limitation.
 	 */
-	if (sizeof(unsigned long) * 8 < va_bits) {
+	if (va_bits > BITS_PER_LONG) {
 		ptdev->gpu_info.mmu_features &= ~GENMASK(7, 0);
-		ptdev->gpu_info.mmu_features |= sizeof(unsigned long) * 8;
+		ptdev->gpu_info.mmu_features |= BITS_PER_LONG;
 	}
 
 	return drmm_add_action_or_reset(&ptdev->base, panthor_mmu_release_wq, mmu->vm.wq);