serial: sc26xx: Fix compile breakage

This patch fixes the following compile breakage:

  CC      drivers/tty/serial/sc26xx.o
drivers/tty/serial/sc26xx.c: In function 'read_sc_port':
drivers/tty/serial/sc26xx.c:100: error: implicit declaration of function 'readb'
drivers/tty/serial/sc26xx.c: In function 'write_sc_port':
drivers/tty/serial/sc26xx.c:105: error: implicit declaration of function 'writeb'
drivers/tty/serial/sc26xx.c: In function 'sc26xx_probe':
drivers/tty/serial/sc26xx.c:652: error: implicit declaration of function 'ioremap_nocache'
drivers/tty/serial/sc26xx.c:652: warning: assignment makes pointer from integer without a cast
make[3]: *** [drivers/tty/serial/sc26xx.o] Error 1
make[2]: *** [drivers/tty/serial] Error 2
make[1]: *** [drivers/tty] Error 2
make: *** [drivers] Error 2

Signed-off-by: Alexander Shiyan <shc_work@mail.ru>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>