drm/radeon: use %zu for formatting size_t

Fixes compiler warnings on 32bit.
Signed-off-by: Luca Tettamanti <kronos.it@gmail.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/radeon/radeon_acpi.c

@@ -201,7 +201,7 @@ static int radeon_atif_verify_interface(acpi_handle handle,
 
 	size = *(u16 *) info->buffer.pointer;
 	if (size < 12) {
-		DRM_INFO("ATIF buffer is too small: %lu\n", size);
+		DRM_INFO("ATIF buffer is too small: %zu\n", size);
 		err = -EINVAL;
 		goto out;
 	}
@@ -485,7 +485,7 @@ static int radeon_atcs_verify_interface(acpi_handle handle,
 
 	size = *(u16 *) info->buffer.pointer;
 	if (size < 8) {
-		DRM_INFO("ATCS buffer is too small: %lu\n", size);
+		DRM_INFO("ATCS buffer is too small: %zu\n", size);
 		err = -EINVAL;
 		goto out;
 	}