BugLink: http://bugs.launchpad.net/bugs/1546572

Enable CP register/instruction error interrupts. Useful
for debugging command stream problems.
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
(cherry picked from commit 1d22a454)
Signed-off-by: Alberto Milone <alberto.milone@canonical.com>
Signed-off-by: Tim Gardner <tim.gardner@canonical.com>