[SERIAL] Make uart_line_info() correctly tell MMIO from I/O port

/proc/tty/driver/serial incorrectly claims that UARTs having iotype of
UPIO_MEM32, UPIO_AU, or UPIO_TSI are I/O mapped.

Signed-off-by: Sergei Shtylyov <sshtylyov@ru.mvista.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>