ASoC: codecs: wcd938x: fix incorrect used of portid
In the Linux kernel, the following vulnerability has been resolved:

ASoC: codecs: wcd938x: fix incorrect used of portid

Mixer controls have the channel id in mixer->reg, which is not same
as port id. port id should be derived from chan_info array.
So fix this. Without this, its possible that we could corrupt
struct wcd938x_sdw_priv by accessing port_map array out of range
with channel id instead of port id.