net: lance,ni64: don't build for ARM

The ni65 and lance ethernet drivers manually program the ISA DMA
controller that is only available on x86 PCs and a few compatible
systems. Trying to build it on ARM results in this error:

ni65.c: In function 'ni65_probe1':
ni65.c:496:62: error: 'DMA1_STAT_REG' undeclared (first use in this function)
     ((inb(DMA1_STAT_REG) >> 4) & 0x0f)
                                                              ^
ni65.c:496:62: note: each undeclared identifier is reported only once for each function it appears in
ni65.c:497:63: error: 'DMA2_STAT_REG' undeclared (first use in this function)
     | (inb(DMA2_STAT_REG) & 0xf0);

The DMA1_STAT_REG and DMA2_STAT_REG registers are only defined for
alpha, mips, parisc, powerpc and x86, although it is not clear
which subarchitectures actually have them at the correct location.

This patch for now just disables it for ARM, to avoid randconfig
build errors. We could also decide to limit it to the set of
architectures on which it does compile, but that might look more
deliberate than guessing based on where the drivers build.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: David S. Miller <davem@davemloft.net>