build: remove GREP_OPTIONS export from rules.mk, defining it in the top-level Makefile is enough

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

SVN-Revision: 39982

rules.mk

@@ -16,9 +16,6 @@ include $(TOPDIR)/include/verbose.mk
 
 export TMP_DIR:=$(TOPDIR)/tmp
 
-GREP_OPTIONS=
-export GREP_OPTIONS
-
 qstrip=$(strip $(subst ",,$(1)))
 #"))