base-files: fix user creation on sysupgrade with few opkg control files

If only a single opkg control file exists (which can happen with
CONFIG_CLEAN_IPKG), grep would not print the file name by default. Instead
of forcing it using -H, we just switch to -l (print only file names) and
get rid of the cut.

Add -s to suppress an error message when no control files exist.

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

package/base-files/files/etc/uci-defaults/13_fix_group_user

@@ -2,7 +2,7 @@
 
 . /lib/functions.sh
 
-for file in `grep Require-User /usr/lib/opkg/info/*.control | cut -d: -f1`; do
+for file in `grep -sl Require-User /usr/lib/opkg/info/*.control`; do
 	file="${file##*/}"
 	file="${file%.control}"
 	add_group_and_user "${file}"