dracut.sh: harden host_modalias reading

Some weird PPC driver make their modulias unreadable

$ cat /sys/devices/vio/4000/modalias
cat: /sys/devices/vio/4000/modalias: No such device
ifup: do not dhcp on network interface of secondary stack

Configure cmdline to:
 ip=br0:dhcp bridge=br0:bond0 bond=bond0:eth0

By default ifup bond0 will run dhcp on bond0, which is wrong. bond0
isn't the top interface. we should really run dhcp on br0.

So if we ifup an network interface on secondary stack, we should not
dhcp. Fix this issue with this patch.
lvm/mdraid: Fix LVM on MD activation

The 69-dm-lvm-metad.rules set some udev env. variables that makes it
possible to detect the right time to activate LVM on MD. The MD is very
similar to DM during activation - it's usable only after proper device
activation - the CHANGE event. We need to make a difference between a
CHANGE event that comes from this activation and CHANGE event that is
the outcome of the WATCH udev rule (otherwise we'd end up with LVM
activation done on each CHANGE event - which is wrong).

So we need the udev databse to be persistent during pivot to root fs
even for MD devices.
mdraid/module-setup.sh: install configs from /etc/mdadm.conf.d

/etc/mdadm.conf.d directory is supported since mdadm-3.3
mdraid/module-setup.sh: fixes for mdadm-3.2.6+

mdadm-3.2.6+:
Incremental assembly rule contains "--offroot" arg. Update
regexp to catch this variant.

mdadm-3.3+:
Rules was splitted into two files: 63-md-raid-arrays.rules
and 64-md-raid-assembly.rules. Install them both and edit
the latter.