PM / devfreq: bw_hwmon: Add support for configuring byte MID match

Add support to configure the byte MID match value from DT.

Change-Id: I5848aef98f15c6de9fe0fae0a1188a17810a5ef5
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
[avajid@codeaurora.org: made minor styling changes]
Signed-off-by: Amir Vajid <avajid@codeaurora.org>