[PATCH] ppc32: Fix MPC83xx IPIC external interrupt pending register offset

The pending registers for IRQ1-IRQ7 were pointing to the interrupt pending
register instead of the external one.

Signed-off-by: Tony Li <Tony.Li@freescale.com>
Signed-off-by: Kumar Gala <kumar.gala@freescale.com>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>