base/init: set the firmware loading timeout to 600

Kernel defaults to 60, but this might be too low, if the machine is
under heavy load, so we increase this to the udev timeout.
git2spec.pl: no signature
kernel-modules/installkernel: s/blk_init_queue/blk_cleanup_queue/g

using "blk_cleanup_queue" will pickup also the nvme driver

https://bugzilla.redhat.com/show_bug.cgi?id=1041484
iscsi/parse-iscsiroot.sh: call iscsistart regardless

call iscsistart, even if no network config is given or
- link down temporarily down
- changed MAC address
- replaced/swapped NIC
- misconfigured kernel command line

https://bugzilla.redhat.com/show_bug.cgi?id=1099603
dracut.conf.5: add install_items to man page

also fixed whitespace stuff

https://bugzilla.redhat.com/show_bug.cgi?id=1041484
rootfs-block: add support for the rootfallback= kernel cmdline option

backport of the rootfallback= kernel cmdline option

https://bugzilla.redhat.com/show_bug.cgi?id=737687