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.

Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Tested-by: Keita Kobayashi <keita.kobayashi.ym@renesas.com>
Acked-by: Geert Uytterhoeven <geert+renesas@glider.be>
Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>