The clock is enabled in the tmio_mmc_host_probe().  It also prevents
drivers from performing platform-specific settings before mmc_add_host()
because the register access generally requires a clock.

Enable/disable the clock in drivers' probe/remove.  Also, I passed
tmio_mmc_data to tmio_mmc_host_alloc() because renesas_sdhi_clk_enable()
needs it to get the private data from tmio_mmc_host.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Reviewed-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>