Fix the formatting of some comments in 8250.c, and add a note that the
register_serial / unregister_serial shouldn't be used in new code.

We do this here in preference to adding to linux/serial.h, since that is used
by a number of non-8250 drivers which pretend to be 8250.  It is not known
whether it would be appropriate to do so.
Signed-off-by: Russell King <rmk@arm.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>