board: qemu_arc: disable test: tests/kernel/mem_protect/mem_protect

This test fails on qemu_arc_{em|hs} consistently,
due to bug in quem_arc, details:
https://github.com/foss-for-synopsys-dwc-arc-processors/qemu/issues/14

.
To get clean results we need to disable this test until the
bug is fixed and fix gets propagated to new Zephyr-SDK.

Signed-off-by: Watson Zeng <zhiwei@synopsys.com>