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
diff --git a/example/default-suites.conf b/example/default-suites.conf
index 7ff8470..8d692fa 100644
--- a/example/default-suites.conf
+++ b/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