sh: sh-sci: sh7377 and sh73a0 build fixes

Fix sh7377 and sh73a0 build failure:

drivers/tty/serial/sh-sci.c: In function 'scif_txfill':
drivers/tty/serial/sh-sci.c:338: error: implicit declaration of function 'sci_SCTFDR_in'
drivers/tty/serial/sh-sci.c: In function 'scif_rxfill':
drivers/tty/serial/sh-sci.c:351: error: implicit declaration of function 'sci_SCRFDR_in'
make[3]: *** [drivers/tty/serial/sh-sci.o] Error 1
make[2]: *** [drivers/tty/serial] Error 2
make[1]: *** [drivers/tty] Error 2
make: *** [drivers] Error 2

Signed-off-by: Magnus Damm <damm@opensource.se>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>