mmc: sh_mmcif: remove unnecessary int clk from struct sh_mmcif_host
struct sh_mmcif_host has 1) int clk, 2) struct clock *hclk,
and host->clk = clk_get_rate(host->hclk).
This int clk is not necessary. Let's remove it.
And, current hclk is confusable naming. Let's rename it to clk.