[*] Initramfs: Fix configuring network before updater

Wait for 3 seconds appear resolv.conf file before running updater.
If resolv.conf not appear then use default nameserver: 8.8.8.8

Add two missed in initramfs scripts that uses in specific cases:
 1. When rootfs used via nfs
 2. When dns setted manually

Signed-off-by: Anton Sergeev <Anton.Sergeev@elecard.ru>