devfreq: bwmon: Increase the IOPercentage limits to 400

The IO percentage limits the values to 100, increase it
since some devices might need a higher value.

Change-Id: I7f19017b426832d9a1a11bd02195a4d15634c041
Signed-off-by: Rama Aparna Mallavarapu <aparnam@codeaurora.org>