Add testsuite + scenarios to test nanoBTS multiTRX

Currently only 2 nanoBTS in the 900 band are attached together as a
multiTRX setup. We thus set num_trx to 2 and set channel allocator
descending to force the BTS to use the 2nd TRX when allocating channels.

Change-Id: I12e1bcb047c4efac5693cf725739e0ce2e0532ee

example/default-suites.conf

@@ -53,8 +53,10 @@
 - voice:nanobts+band-900+mod-bts0-ts-tchf
 - voice:nanobts+band-900+mod-bts0-ts-tchh
 - voice:nanobts+band-900+mod-bts0-dynts-ipa
+- voice:nanobts+band-900+mod-bts0-numtrx2+mod-bts0-chanallocdescend
 - gprs:nanobts+band-900
 - gprs:nanobts+band-900+mod-bts0-dynts-ipa
+- gprs:nanobts+band-900+mod-bts0-numtrx2+mod-bts0-chanallocdescend
 - smpp
 - aoip_smpp
 - aoip_encryption

example/defaults.conf

@@ -54,11 +54,22 @@ bsc_bts:
     - phys_chan_config: TCH/F
     - phys_chan_config: TCH/F
     - phys_chan_config: TCH/F
-    - phys_chan_config: TCH/F
-    - phys_chan_config: TCH/F
+    - phys_chan_config: PDCH
+    - phys_chan_config: PDCH
 
 osmo_bts_octphy:
   max_trx: 2
 
 nanobts:
   max_trx: 2
+  trx_list:
+  - {}
+  - timeslot_list:
+    - {}
+    - {}
+    - {}
+    - {}
+    - {}
+    - {}
+    - phys_chan_config: TCH/F # nanobts only supports PDCH in TRX0.
+    - phys_chan_config: TCH/F

example/scenarios/mod-bts0-chanallocdescend.conf

@@ -0,0 +1,3 @@
+modifiers:
+  bts:
+  - channel_allocator: descending