trxcon: trxcon_fsm: permit loop [P]DCH transitions

According to 3GPP TS 44.004, Figure 5.1, it's absolutely legal to
perform loop transitions in state 'DCH' (i.e. from 'DCH' to 'DCH').

This kind of transition is needed in the following cases:

* on reciept of RR FREQUENCY REDEFINITION,
* on reciept of RR ASSIGNMENT REQUEST,
* on reciept of RR HANDOVER REQUEST,

when going back from state 'DCH' to state 'BCH' is not required nor
actually desired.  In context of the trxcon_fsm, this applies to
both TRXCON_ST_DEDICATED and TRXCON_ST_PACKET_DATA, as they both
represent what's defined as 'DCH' in the Figure 5.1.

Change-Id: I3b402ec84610a5df744d9b06e5f7dab7a9a3ddad
Related: OS#5599
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M src/host/trxcon/src/trxcon_fsm.c
1 file changed, 10 insertions(+), 2 deletions(-)