[PATCH] drivers/mca: handle sysfs errors

Also includes a kmalloc->kzalloc cleanup.

Signed-off-by: Jeff Garzik <jeff@garzik.org>
Cc: James Bottomley <James.Bottomley@steeleye.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>