Patch from Lennert Buytenhek
  
There are thirteen different IRQs chained off IRQ_ERR_STATUS, one for
each possible error class that the IXP can signal an interrupt for, but
there are no in-tree users of these interrupts, and it doesn't make much
sense to treat them as separate interrupts if we can just have one
handler checking each of the thirteen errors in one go instead.
  
Besides that, the error interrupt handling can't even have been working
properly in the first place as the chained handler was testing the wrong
bits in the IRQ_ERR_STATUS register.
  
So this patch rips it all out.
  

Signed-off-by: Lennert Buytenhek
Signed-off-by: Deepak Saxena
Signed-off-by: Russell King