[PATCH] Char: moxa, remove useless variables

Remove temporary or once used variables, that can be defined locally to
save some bytes.

Signed-off-by: Jiri Slaby <jirislaby@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>