pcu_l1_if_phy: add new PHY API function to disconnect PDCH

There is a function l1if_connect_pdch, but no complementary function
like we have it with l1if_open_pdch and l1if_close_pdch. The reason for
this is that the PHY implementations that rely on a femtocell DSP do not
need to disconnect the pdch explcitly. However, the planned support for
the E1 based Ercisson RBS CCU will require an explicit disconnect. So
lets add a function call for this.

Change-Id: Ied88f3289bda87c48f5f9255c4591470633cc805
Related: OS#5198
diff --git a/src/pcu_l1_if.cpp b/src/pcu_l1_if.cpp
index fdee83d..258a118 100644
--- a/src/pcu_l1_if.cpp
+++ b/src/pcu_l1_if.cpp
@@ -918,6 +918,10 @@
 				     trx_nr, ts_nr, pdch->tsc, pdch->fh.enabled ? "yes" : "no");
 			} else {
 				if (pdch->is_enabled()) {
+#ifdef ENABLE_DIRECT_PHY
+					if ((info_ind->flags & PCU_IF_FLAG_SYSMO))
+						l1if_disconnect_pdch(bts->trx[trx_nr].fl1h, ts_nr);
+#endif
 					pcu_tx_act_req(bts, pdch, 0);
 					pdch->disable();
 				}