Change the clk_enable operation to take a pointer to the struct
tmio_mmc_host and have it set f_max.  For consistency, also change the
clk_disable operation to take a pointer to struct tmio_mmc_host.
Signed-off-by: Ben Hutchings <ben.hutchings@codethink.co.uk>
Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>