ARM: kprobes: Add test cases for stack consuming instructions

These have extra 'checker' functions associated with them so lets make
sure those get covered by testing. As they may create uninitialised
space on the stack we also update the test code to ensure such space is
consistent between test runs. This is done by disabling interrupts in
setup_test_context().

Signed-off-by: Jon Medhurst <tixy@linaro.org>