bsc_api.c: actually log with context

bsc_api.c notoriously lacks log context. Provide gsm_lchan_name() and/or
bsc_subscr_name() in roughly a million instances, using new LOGPLCHAN macro.

Add LOGPLCHAN() to gsm_data.h, to encourage use of it in other .c files.

Change-Id: If469defcc6fe8950dac5df61db3f39d297893318
2 files changed