mISDN: Add layer1 prim MPH_INFORMATION_REQ

mISDN: Add layer1 prim MPH_INFORMATION_REQ

MPH_INFORMATION provides full D- and B-Channel status overview

- new layer1 primitive: MPF_INFORMATON_REQ
- layer1 replies with MPH_INFORMATION_IND containing
   - dch->[state,Flags,nrbchan]
   - bch[]->[protocol,Flags]
- hardware driver should send MPH_INFORMATION_IND
  on all ph state changes and BChannel state changes to MISDN_ID_ANY

Signed-off-by: Martin Bachem <m.bachem@gmx.de>
Signed-off-by: Karsten Keil <kkeil@suse.de>