net: smc91x: dont't use SMC_outw for fixing up halfword-aligned data

SMC_outw invokes an endian-aware I/O accessor, which may change the data
endianness before writing to the device. This is not suitable for data
transfers where the memory buffer is simply a string of bytes that does
not require any byte-swapping.

This patches fixes the smc91x SMC_PUSH_DATA macro so that it uses the
string I/O accessor for outputting the leading or trailing halfwords on
halfword-aligned buffers.

Cc: <netdev@vger.kernel.org>
Cc: Nicolas Pitre <nico@fluxnic.net>
Cc: David S. Miller <davem@davemloft.net>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Acked-by: Nicolas Pitre <nico@linaro.org>
Signed-off-by: David S. Miller <davem@davemloft.net>