net: ks8851-ml: Fix IO operations, again

commit 8262e6f9 upstream.

This patch reverts 58292104 ("net: ks8851-ml: Fix 16-bit IO operation")
and edacb098 ("net: ks8851-ml: Fix 16-bit data access"), because it
turns out these were only necessary due to buggy hardware. This patch adds
a check for such a buggy hardware to prevent any such mistakes again.

While working further on the KS8851 driver, it came to light that the
KS8851-16MLL is capable of switching bus endianness by a hardware strap,
EESK pin. If this strap is incorrect, the IO accesses require such endian
swapping as is being reverted by this patch. Such swapping also impacts
the performance significantly.

Hence, in addition to removing it, detect that the hardware is broken,
report to user, and fail to bind with such hardware.

Fixes: 58292104 ("net: ks8851-ml: Fix 16-bit IO operation")
Fixes: edacb098 ("net: ks8851-ml: Fix 16-bit data access")
Signed-off-by: Marek Vasut <marex@denx.de>
Cc: David S. Miller <davem@davemloft.net>
Cc: Lukas Wunner <lukas@wunner.de>
Cc: Petr Stetiar <ynezz@true.cz>
Cc: YueHaibing <yuehaibing@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>