mxser: remove MOXA_GET_MAJOR deprecated ioctl

MOXA_GET_MAJOR was deprecated in commit 41aee9a1 (Char: mxser, ioctl
cleanup) in 2008. Remove this ioctl finally.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Link: https://lore.kernel.org/r/20210618061516.662-23-jslaby@suse.cz


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>