ARC: Fix Linux kernel comilation for ARC700

Without this fix we're getting the following error on attempt to build
Linux kernel:
--------------------------------->8---------------------------------
xfrm4_mode_tunnel.s: Assembler messages:
xfrm4_mode_tunnel.s:188: Error: operand out of range (128 is not between -
128 and 127)
--------------------------------->8---------------------------------

The fix is taken from
foss-for-synopsys-dwc-arc-processors/gcc@d8d716f
and it is supposed to be merged in upstream GCC sources soonish.

Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>