ipmi: Improve error messages on failed irq enable

When the interrupt enable message returns an error, the messages are
not entirely accurate nor helpful.  So improve them.

Signed-off-by: Corey Minyard <cminyard@mvista.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>