package/binutils: finalize the bump ARC tools to arc-2017.03-rc2

The commit bumping ARC tools to arc-2017.03-rc2 [1] forgot to
update the ARC tools version in binutils.mk

[1] 04373728

Fixes:
http://autobuild.buildroot.net/results/f9c/f9c40610209fc22ac8c0db6bd57bd3b11bbe6d9c



Signed-off-by: Romain Naour <romain.naour@gmail.com>
Cc: Alexey Brodkin <abrodkin@synopsys.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>