[PATCH] Serial: Remove {un,}register_serial from 68328serial.c

68328serial.c does not make use of register_serial/unregister_serial,
which is traditionally used to register 8250-compatible UARTs with
the 8250-compatible serial driver.

Acked-by: David McCullough
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>