msm: vidc: Change governor names to be less than 15 chars

Devfreq governor names are (implicitly) limited to 15 characters.
"msm-vidc-bw-vmem" was 17 chars, which caused a buffer overflow.

Change-Id: I03577be3e6384109f75263c43a66d3317087e1f7
Signed-off-by: Deva Ramasubramanian <dramasub@codeaurora.org>