mmc: tmio: deprecate "toshiba, mmc-wrprotect-disable" DT property

This property is equivalent to "disable-wp" defined in
Documentation/devicetree/bindings/mmc/mmc.txt

The TMIO MMC core calls mmc_of_parse(), and it sets
MMC_CAP2_NO_WRITE_PROTECT if "disable-wp" property is present.

We do not need a vendor-specific property to do the same thing.

Let's remove the description from the dt-binding to prevent new boards
from using it.

I am keeping the driver code for existing DT files, but added
comments that this is deprecated.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Acked-by: Rob Herring <robh@kernel.org>
Reviewed-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Tested-by: Wolfram Sang <wsa+renesas@sang-engineering.com>