gcc: the special workaround for ARC is no longer required

It seems with the change to gcc 6.x based toolchain this
workaround is no longer required. Tested with an arc hs toolchain.

Signed-off-by: Waldemar Brodkorb <wbx@openadk.org>
Acked-by: Alexey Brodkin <abrodkin@synopsys.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>