allow 'flash_banks' command to give GDB output

The 'flash banks' command produces a list that needs to be formatted
properly for GDB's 'mem info' to work properly.  The flash_banks TCL
wrapper provided this formatting, but wrappers no longer work for
second-level commands as they did in the past.  With this patch,
the 'flash_banks' command can be used with the new command syntax
and display the required information.

src/flash/startup.tcl

@@ -5,7 +5,7 @@
 proc flash_banks {} {
 	set i 0
 	set result ""
-	foreach {a} [ocd_flash_banks] {
+	foreach {a} [ocd_flash banks] {
 		if {$i > 0} {
 			set result "$result\n"
 		}