mmc: tmio: remove TMIO_MMC_WRPROTECT_DISABLE

The use of this flag has been replaced with MMC_CAP2_NO_WRITE_PROTECT.
No platform defines this flag any more.  Remove.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Acked-by: Lee Jones <lee.jones@linaro.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>