Command usage cleanup

Remove command name from all command "usage" fields and update
common/command.c to display "name - usage" instead of
just "usage". Also remove newlines from command usage fields.

Signed-off-by: Peter Tyser <ptyser@xes-inc.com>

common/cmd_strings.c

@@ -41,6 +41,6 @@ int do_strings(cmd_tbl_t *cmdtp, int flag, int argc, char *argv[])
 }
 
 U_BOOT_CMD(strings, 3, 1, do_strings,
-	"strings - display strings\n",
+	"display strings",
 	"<addr> [byte count]\n"
 	"    - display strings at <addr> for at least [byte count] or first double NUL\n");