powerpc/85xx: handle the eLBC error interrupt if it exists in dts

On P1020, P1021, P1022, and P1023, eLBC event interrupts are routed
to internal interrupt 3 while ELBC error interrupts are routed to
internal interrupt 0.  We need to call request_irq for each.

Signed-off-by: Shaohui Xie <Shaohui.Xie@freescale.com>
Signed-off-by: Wang Dongsheng <dongsheng.wang@freescale.com>
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>
[scottwood@freescale.com: reworded commit message and fixed author]
Signed-off-by: Scott Wood <scottwood@freescale.com>