osmo-nitb supports the modification of an lchan if the lchan is
compatible but in the wrong mode. This feature was dropped in the
transition to AoIP/bsc-split. However, osmo-bsc still has code to
generate and parse the messeages, but the FSMs do not support a mode
modify yetm
Lets add handling for mode-modify to the lchan_fsm and assignment_fsm in
order to support mode modify again
Change-Id: I2c5a283b1ee33745cc1fcfcc09a0f9382224e2eb
Related: OS#4549
These reflect the plan for refactoring, and will be implemented by
I82e3f918295daa83274a4cf803f046979f284366 and
Id7a4407d9b63be05ce63f5f2768b7d7e3d5c86fb
Change-Id: I29e31b753e23a4207662e0e385a337e7df836f45
Philipp Maier
Neels Hofmeyr