raid-2.2.17-A0 cleanup for LVM

[Andrea Arcangeli]

This patch cleanups the new raid code so that we have a chance that LVM on
top of RAID will keep working. It's untested at the moment.

        
ftp://ftp.*.kernel.org/pub/linux/kernel/people/andrea/patches/v2.2/2.2.17pre13/raid-2.2.17-A0/raid-lvm-cleanup-1

Andrea