udelay() does not work on some architectures for values above
2000, in particular on ARM:

ERROR: "__bad_udelay" [drivers/scsi/bfa/bfa.ko] undefined!
Reported-by: NVagrant Cascadian <vagrant@debian.org>
Signed-off-by: NBen Hutchings <ben@decadent.org.uk>
Signed-off-by: NJames Bottomley <JBottomley@Parallels.com>