msm: kgsl: Update bandwidth vote using the right API

When a gpubw-dev node is not populated in a dtsi, pwrctrl_init
registers the bus votes through the msm_bus_scale_register_client.
Make sure we don't call the vbif governor APIs in such a case to
update the bandwidth.

Change-Id: I2125c4093c259737c73db652b38cb5e30206d222
Signed-off-by: Suman Tatiraju <sumant@codeaurora.org>