net: tulip: winbond-840: fix build for UML

On i386, when builtin (not a loadable module), the winbond-840 driver
inspects boot_cpu_data to see what CPU family it is running on, and
then acts on that data. The "family" struct member (x86) does not exist
when running on UML, so prevent that test and do the default action.

Prevents this build error on UML + i386:

../drivers/net/ethernet/dec/tulip/winbond-840.c: In function ‘init_registers’:
../drivers/net/ethernet/dec/tulip/winbond-840.c:882:19: error: ‘struct cpuinfo_um’ has no member named ‘x86’
  if (boot_cpu_data.x86 <= 4) {

Fixes: 68f5d3f ("um: add PCI over virtio emulation driver")
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Cc: linux-um@lists.infradead.org
Cc: Jeff Dike <jdike@addtoit.com>
Cc: Richard Weinberger <richard@nod.at>
Cc: Anton Ivanov <anton.ivanov@cambridgegreys.com>
Link: https://lore.kernel.org/r/20211014050606.7288-1-rdunlap@infradead.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/net/ethernet/dec/tulip/winbond-840.c

@@ -879,7 +879,7 @@ static void init_registers(struct net_device *dev)
 		8000	16 longwords		0200 2 longwords	2000 32 longwords
 		C000	32  longwords		0400 4 longwords */
 
-#if defined (__i386__) && !defined(MODULE)
+#if defined (__i386__) && !defined(MODULE) && !defined(CONFIG_UML)
 	/* When not a module we can work around broken '486 PCI boards. */
 	if (boot_cpu_data.x86 <= 4) {
 		i |= 0x4800;