net/tulip: don't warn about unknown ARM architecture

ARM has 32-byte cache lines, which according to the comment in
the init registers function seems to work best with the default
value of 0x4800 that is also used on sparc and parisc.

This adds ARM to the same list, to use that default but no
longer warn about it.
Signed-off-by: NArnd Bergmann <arnd@arndb.de>
Acked-by: NGrant Grundler <grundler@parisc-linux.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

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

@@ -904,7 +904,7 @@ static void init_registers(struct net_device *dev)
 	}
 #elif defined(__powerpc__) || defined(__i386__) || defined(__alpha__) || defined(__ia64__) || defined(__x86_64__)
 	i |= 0xE000;
-#elif defined(CONFIG_SPARC) || defined (CONFIG_PARISC)
+#elif defined(CONFIG_SPARC) || defined (CONFIG_PARISC) || defined(CONFIG_ARM)
 	i |= 0x4800;
 #else
 #warning Processor architecture undefined