bankd: Add GSMTAP functionality for SIM traffic

If a --gsmtap-host (-g) address is specified on the command line, trace
SIM ATRs and APDUs to the given IP. If --gsmtap-slot (-G) is provided,
limit tracing to the specified bank slot number. This feature may be
useful when diagnosing issues with the remote SIM framework.

Added new log category: DGSMTAP

Also, cleaned up alignment in bankd --help output and removed unused -o option.

Change-Id: I05b599858d8758633aa56c3f12f258c27cf42d08
diff --git a/src/debug.h b/src/debug.h
index 88288ca..6e04393 100644
--- a/src/debug.h
+++ b/src/debug.h
@@ -8,6 +8,7 @@
 	DREST,
 	DSLOTMAP,
 	DBANKDW,
+	DGSMTAP,
 };
 
 extern const struct log_info log_info;