[MIPS] Atlas: update interrupt handling

The following change updates the Atlas interrupt handling to match that
of Malta.  Tested with a 5Kc and a 34Kf successfully.

Signed-off-by: Maciej W. Rozycki <macro@mips.com>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
6 files changed