rsl_tx_rf_res(): also report noise levels for PDTCH
rsl_tx_rf_res(): also report noise levels for PDTCH

This information may be useful for the BSC to determine whether
dynamic PDCH timeslots might be better used for new circuit
switched connections, or whether alternative PDCH slots should
be allocated for interference reasons.

Change-Id: I5b4d1da0920e788ac8063cc765fe5b0223c76758
Related: SYS#5313

osmocom/osmo-bts,osmocom/osmo-bts,osmocom/osmo-bts