ARC: build: don't force usage of llock and swape instructions
This is because some old ARC750 cores lack these instructions.
We now rely on the default for the toolchain driver:
-mcpu=A7 won't enable those, while -mcpu=archs will as these
instructions are baseline (and thus is not impacted with this change).
If some arc700 based cpu does have them, it can override the driver
defaults in it's one level up build system.
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
Vineet Gupta