watchdog: RDC321X_WDT always depends on PCI

Without this dependency, platforms not supporting PCI (such as m68k)
report the following build warning when building allmodconfig
or allyesconfig.

drivers/watchdog/rdc321x_wdt.c: In function 'rdc321x_wdt_ioctl':
./arch/m68k/include/asm/uaccess_mm.h:61:1: warning:
	'value' may be used uninitialized in this function

Fixes: f4c3de659054 ("watchdog: Enable COMPILE_TEST where possible")
Signed-off-by: Guenter Roeck <linux@roeck-us.net>