base-files: /lib/functions.sh: ignore errors in insert_modules

Package postinst will pass even names of builtin modules to insert_modules,
leading to postinst failing with error 255. This has been fixed in master
in r5279, but for lede-17.01 this minimal change is preferable.

Fixes FS#645, FS#893.

Signed-off-by: Matthias Schiffer <mschiffer@universe-factory.net>

package/base-files/files/lib/functions.sh

@@ -158,7 +158,7 @@ insert_modules() {
 		if [ -f /etc/modules.d/$m ]; then
 			sed 's/^[^#]/insmod &/' /etc/modules.d/$m | ash 2>&- || :
 		else
-			modprobe $m
+			modprobe $m || :
 		fi
 	done
 }