sunhme: Fix Quattro HME irq registration on proble failures

Currently, the sunhme driver installs SBus Quattro interrupt handler 
when at least one HME card was initialized correctly and at least one 
Quattro card is present. This breaks when a Quattro card fails 
initialization for whatever reason - IRQ is registered and OOPS happens 
when it fires.

The solution, as suggested by David Miller, was to keep track which 
cards of the Quattro bundles have been initialized, and request/free the 
Quattro IRQ only when all four devices have been successfully 
initialized.

The patch only touches SBus initialization - PCI init already resets the 
card pointer to NULL on init failure.

The patch has been tested on Sun E3500 with SBus and PCI single HME 
cards and one PCI Quattro HME card in a situation where any PCI card 
failed init when the SBus routines tried to init them by mistake.

Additionally it replaces Quattro request_irq panic with error return - 
if this card fails to work, at least let the others work.

Tested on E450 with PCI HME and PCI Quad HME.

[ Minor coding style fixups -DaveM ]

Signed-off-by: Meelis Roos <mroos@linux.ee>
Signed-off-by: David S. Miller <davem@davemloft.net>