Char: mxser, simplify mxser_get_serial_info

Initialize temp structure directly with proper values without first zeroing
it and setting later as suggested by Jan.

Signed-off-by: Jiri Slaby <jirislaby@gmail.com>
Cc: Jan Engelhardt <jengelh@computergmbh.de>
Reviewed-by: Alan Cox <alan@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>