watchdog: simatic: add PCI dependency

watchdog: simatic: add PCI dependency

The simatic-ipc driver no longer depends on PCI, but its watchdog portion
still needs it, otherwise P2SB runs into a build  failure:

WARNING: unmet direct dependencies detected for P2SB
  Depends on [n]: PCI [=n] && X86 [=y]
  Selected by [m]:
  - SIEMENS_SIMATIC_IPC_WDT [=m] && WATCHDOG [=y] && SIEMENS_SIMATIC_IPC [=y]

drivers/platform/x86/p2sb.c:121:3: error: call to undeclared function 'pci_bus_write_config_dword'; ISO C99 and later do not support implicit function declarations [-Wimplicit-function-declaration]
                pci_bus_write_config_dword(bus, devfn_p2sb, P2SBC, 0);

Add back the minimum dependendency to make it build in random
configurations again.

Fixes: b72da71ce24b ("platform/x86: simatic-ipc: drop PCI runtime depends and header")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Link: https://lore.kernel.org/r/20230814073924.1066390-1-arnd@kernel.org
Signed-off-by: Hans de Goede <hdegoede@redhat.com>