Merge branch 'gigaset_modem_response'

Tilman Schmidt says:

====================
isdn/gigaset: restructure modem response parser

This series of patches restructures the Gigaset ISDN driver's
modem response parser to improve code readability and conform
better to the device's specification and actual behaviour.
Could you please merge these through net-next?
====================

Signed-off-by: David S. Miller <davem@davemloft.net>