toolchain: Bump ARC tools to arc-2017.03-rc2

This commit bumps ARC toolchain to arc-2017.03-rc2

Please note that it is a release candidate and it might contain some
breakages, please don't use it for production builds.

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