Make SMIC driver ignore EVT_AVAIL and SMS_ATN bits in flags register, as
they're used by systems management interrupts, not the host OS.

Make the OEM0 Data Available handler work for pre-IPMI 1.5 systems from Dell
too.

Without these two fixes, PowerEdge 2650 and other similar systems with SMIC
may hang a process (modprobe or anything using /dev/ipmi0).
Signed-off-by: Matt Domsch <Matt_Domsch@dell.com>
Signed-off-by: Corey Minyard <minyard@acm.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>