kernel: _MOVE_INSTR needs to be defined for CONFIG_ARC

In order to build test/kernel/test_stackprot/microkernel for the ARC,
the _MOVE_INSTR needs to define what the move instruction is for this
target.

Change-Id: I087cc5baa4c41297ce52323556e94aab424aa891
Signed-off-by: Chuck Jordan <cjordan@synopsys.com>