parisc: don't enable irqs unconditionally in handle_interruption()

If the previous context had interrupts disabled, we should better
keep them disabled. This was noticed in the unwinding code where
a copy_from_kernel_nofault() triggered a page fault, and after
the fixup by the page fault handler interrupts where suddenly
enabled.

Signed-off-by: Sven Schnelle <svens@stackframe.org>
Signed-off-by: Helge Deller <deller@gmx.de>