lrdp-v2: improve error message when !vmlinux && !autodumpdir

Currently, if the user doesn't specify a vmlinux image or an
autodumpdir (like when running ramparse.py with absolutely no arguments)
they get a big ugly python stacktrace and no helpful error message. Fix
this.

Change-Id: I2d5aaaae5c8afd651ef48cfbd8f974227c2032fe

linux-ramdump-parser-v2/ramparse.py

@@ -128,6 +128,10 @@ if __name__ == '__main__':
             sys.exit(1)
 
     if options.vmlinux is None:
+        if options.autodump is None:
+            print_out_str("No vmlinux or autodump dir given. I can't proceed!")
+            parser.print_usage()
+            sys.exit(1)
         autovm = os.path.join(options.autodump, 'vmlinux')
         if os.path.isfile(autovm):
             options.vmlinux = autovm