bts: Fix race condition in f_dyn_ipa_pdch_(de)act

Test BTS_Tests.TC_dyn_osmo_pdch_act_deact was sporadically failing due
to receiving IND_INFO on the PCU port with pdch_mask related TS bit set
to 0 after sending a PDCH ACT. That happened due to a race condition
because PCU send IND_INFO periodically. As a result, it can happen that
BTS sends an IND_INFO after PCU.clear was called and before the PDCH ACT
is handled.

Change-Id: If11ef05d97aa5f6caaa731f3817c1fecfc3edf7c
1 file changed