Support arm in the platform_KernelErrorPaths test.

Turn off the nmiwatchdog test for arm since arm does not have an NMI
mechanism to reliably detect this condition.
Reduce the size of the 'nullptr' string since arm and x86 have slightly
different strings.

BUG=chromium-os:24130
TEST=platform_KernelErrorPaths should now work on arm

Change-Id: I8cd10a42f09a8243148449f3926a5f24727240f9
Reviewed-on: https://gerrit.chromium.org/gerrit/19698
Tested-by: Bryan Freed <bfreed@chromium.org>
Reviewed-by: Grant Grundler <grundler@chromium.org>
Commit-Ready: Bryan Freed <bfreed@chromium.org>
1 file changed