Some fixes and cleanups from the linux-mac68k repo.  Fix mac_esp by clearing
the VIA2 SCSI IRQ flag before the SCSI IRQ handler is invoked.  Also fix a
race condition caused by unmasking a nubus slot IRQ then setting the relevant
nubus_active bit.
Signed-off-by: NFinn Thain <fthain@telegraphics.com.au>
Signed-off-by: NRoman Zippel <zippel@linux-m68k.org>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>