fwparam_ibft: Do not check for 'Block Valid Flag'

Some iBFT firmware only sets the 'Firmware Boot Selected Flag'
(Bit 1), but not the 'Block Valid Flag' (Bit 0) in the NIC
flags. So we need to loosen the check and accept any value
in the 'flags' field.

References: bnc#902183

Signed-off-by: Hannes Reinecke <hare@suse.de>
Updated build script to use current branch by
default, and removed unused RELEASE variable
Updated changes file for Hannes commit
Added bug number to changes file