vty: allow configuring db path from cfg file

So far, the cmdline argument was the only way to set a database file.
Add a similar config to VTY as 'msc' / 'sms-database'. The cmdline arg is stronger
than the 'database' cfg item. DB is not reloaded from VTY command.

Change-Id: I18d954c30fcceb0b36a620b927fd3a93dcc79f49
diff --git a/tests/msc_vlr/msc_vlr_test_ss.err b/tests/msc_vlr/msc_vlr_test_ss.err
index ca18094..3b324d3 100644
--- a/tests/msc_vlr/msc_vlr_test_ss.err
+++ b/tests/msc_vlr/msc_vlr_test_ss.err
@@ -1,6 +1,6 @@
 DLMGCP MGCP client: using endpoint domain '@mgw'
 full talloc report on 'msgb' (total      0 bytes in   1 blocks)
-talloc_total_blocks(tall_bsc_ctx) == 20
+talloc_total_blocks(tall_bsc_ctx) == 21
 
 ===== test_ss_ussd_mo_geran
 - Location Update request causes a GSUP LU request to HLR
@@ -241,7 +241,7 @@
 ===== test_ss_ussd_mo_geran: SUCCESS
 
 full talloc report on 'msgb' (total      0 bytes in   1 blocks)
-talloc_total_blocks(tall_bsc_ctx) == 20
+talloc_total_blocks(tall_bsc_ctx) == 21
 
 ===== test_ss_ussd_no_geran
 - Location Update request causes a GSUP LU request to HLR
@@ -507,8 +507,8 @@
 ===== test_ss_ussd_no_geran: SUCCESS
 
 full talloc report on 'msgb' (total      0 bytes in   1 blocks)
-talloc_total_blocks(tall_bsc_ctx) == 20
+talloc_total_blocks(tall_bsc_ctx) == 21
 
 full talloc report on 'msgb' (total      0 bytes in   1 blocks)
-talloc_total_blocks(tall_bsc_ctx) == 20
+talloc_total_blocks(tall_bsc_ctx) == 21