always use busybox grep in scripts

This fixes a bug where I was getting "binary file
~/.local/modem/modemlog.tsv matches" instead of getting a list of recent
contacts in sxmo_modemtext.sh. Turns out, having gnu grep breaks the behaviour
of showing a list of contacts. This patch ensures we are always using busybox
grep.

Signed-off-by: Maarten van Gompel <proycon@anaproy.nl>

scripts/core/sxmo_common.sh

@@ -46,6 +46,7 @@ fi
 alias xargs="busybox xargs"
 alias less="busybox less"
 alias tail="busybox tail"
+alias grep="busybox grep"
 
 SXMO_COMMON_INCLUDED=1