toolchain/helpers.mk: remove unused argument of check_arm_abi

The check_arm_abi function takes as second argument the path to the
cross-readelf, but does not use it. Therefore, this commit gets rid of
this unnecessary argument.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

toolchain/helpers.mk

@@ -277,7 +277,6 @@ check_uclibc = \
 #
 check_arm_abi = \
 	__CROSS_CC=$(strip $1) ; \
-	__CROSS_READELF=$(strip $2) ; \
 	EXT_TOOLCHAIN_TARGET=`LANG=C $${__CROSS_CC} -v 2>&1 | grep ^Target | cut -f2 -d ' '` ; \
 	if ! echo $${EXT_TOOLCHAIN_TARGET} | grep -qE 'eabi(hf)?$$' ; then \
 		echo "External toolchain uses the unsuported OABI" ; \