mmc: omap_hsmmc: use devm_clk_get

With devm_clk_get conversion clk_put can be removed in clean up path

Signed-off-by: Balaji T K <balajitk@ti.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Signed-off-by: Chris Ball <chris@printf.net>