sparc32, leon: bugfix in LEON SMP interrupt init

During converting per-cpu ticker to genirq layer some
IRQ initialization code was removed by commit
2cf9530420e446bb61f665d02afeb81070106900 ("sparc32,leon:
per-cpu ticker use genirq per-cpu handler").

This patch reintroduces the code at the same place it was
removed from. IRQ12 - IRQ14 will crash on LEON SMP without
this patch because it will run the SUN4M IRQ trap handler.

Reported-by: Jan Andersson <jan@gaisler.com>
Signed-off-by: Daniel Hellstrom <daniel@gaisler.com>
Signed-off-by: David S. Miller <davem@davemloft.net>