base-files: do not strip fwtool signature data during check

Same reason as in commit 9808bd279927bcd2d3a78d19a55229b93bbbcf05 -
sysupgrade --test must not alter the image in any way

Signed-off-by: Felix Fietkau <[email protected]>

package/base-files/files/lib/upgrade/fwtool.sh

@@ -9,7 +9,7 @@ fwtool_check_signature() {
 		fi
 	}
 
-	if ! fwtool -q -t -s /tmp/sysupgrade.ucert "$1"; then
+	if ! fwtool -q -s /tmp/sysupgrade.ucert "$1"; then
 		echo "Image signature not found"
 		[ "$REQUIRE_IMAGE_SIGNATURE" = 1 -a "$FORCE" != 1 ] && {
 			echo "Use sysupgrade -F to override this check when downgrading or flashing to vendor firmware"