mmc: squash lines for immediate return

These functions can be much simpler by squashing lines for immediate
return.

For *_bind() callbacks, they will be a simple wrapper function of an
upper-level bind API.

For mmc_set_{boot_bus_width,part_conf}, they will be a wrapper of
mmc_switch().

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Reviewed-by: Jaehoon Chung <jh80.chung@samsung.com>
diff --git a/drivers/mmc/rockchip_sdhci.c b/drivers/mmc/rockchip_sdhci.c
index 624029b..c56e1a3 100644
--- a/drivers/mmc/rockchip_sdhci.c
+++ b/drivers/mmc/rockchip_sdhci.c
@@ -62,13 +62,8 @@
 static int rockchip_sdhci_bind(struct udevice *dev)
 {
 	struct rockchip_sdhc_plat *plat = dev_get_platdata(dev);
-	int ret;
 
-	ret = sdhci_bind(dev, &plat->mmc, &plat->cfg);
-	if (ret)
-		return ret;
-
-	return 0;
+	return sdhci_bind(dev, &plat->mmc, &plat->cfg);
 }
 
 static const struct udevice_id arasan_sdhci_ids[] = {