ramips: fix wrong i2s clock unit from kHz to MHz

clk_get_rate returns the current clock rate in Hz for a clock source so
if we divide it by 1M, then we get frequency in MHz and not kHz.

Signed-off-by: Qin Wei <support@vocore.io>
[added missing commit message, and fixed author with SoB from PR message]
Signed-off-by: Petr Štetiar <ynezz@true.cz>

Signed-off-by: Petr Štetiar <ynezz@true.cz>

target/linux/ramips/patches-4.14/0048-asoc-add-mt7620-support.patch

@@ -1007,7 +1007,7 @@ Signed-off-by: John Crispin <blogic@openwrt.org>
 +	if (ret)
 +		goto err_debugfs;
 +
-+	dev_info(i2s->dev, "mclk %luKHz\n", clk_get_rate(i2s->clk) / 1000000);
++	dev_info(i2s->dev, "mclk %luMHz\n", clk_get_rate(i2s->clk) / 1000000);
 +
 +	return 0;
 +