mmc: sunxi: Use devm_mmc_alloc_host() helper

mmc: sunxi: Use devm_mmc_alloc_host() helper

Use new function devm_mmc_alloc_host() to simplify the code.

Cc: Chen-Yu Tsai <wens@csie.org>
Cc: Jernej Skrabec <jernej.skrabec@gmail.com>
Cc: Samuel Holland <samuel@sholland.org>
Cc: linux-sunxi@lists.linux.dev
Reviewed-by: Huacai Chen <chenhuacai@loongson.cn>
Signed-off-by: Binbin Zhou <zhoubinbin@loongson.cn>
Link: https://lore.kernel.org/r/ee7726b1ea37084258a5d8cec67cad12473152c2.1748933789.git.zhoubinbin@loongson.cn
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>