Verifying and handling received MBIM and NCM frames will need
to be different in three areas:
- verifying the NDP signature
- checking valid datagram length
- datagram header manipulation
This makes it inconvenient to share rx_fixup in whole. But
some verification parts are common. Split these out in separate
functions.
Signed-off-by: Bjørn Mork <bjorn@mork.no> Signed-off-by: David S. Miller <davem@davemloft.net>