Update toolchain paths for 4.8.5

The ARC 4.8.5 toolchain doesn't need the /usr and has
different executable names, update for u-boot.

Change-Id: Ib218c9d5e79a10e4efaf9e90aa578d29ca0328fe
diff --git a/Makefile.gfiber b/Makefile.gfiber
index 7442d4a..2a6972c 100644
--- a/Makefile.gfiber
+++ b/Makefile.gfiber
@@ -4,8 +4,8 @@
 
 export ARCH=arm
 export TOP=$(PWD)
-export CROSS_TOOLDIR=$(TOP)/../../toolchains/quantenna/usr/bin/
-export CROSS_PREFIX=arc-buildroot-linux-uclibc-
+export CROSS_TOOLDIR=$(TOP)/../../toolchains/quantenna/bin/
+export CROSS_PREFIX=arc-linux-uclibc-
 export CROSS_COMPILE=$(CROSS_TOOLDIR)/$(CROSS_PREFIX)
 
 version = $(shell ./version)