USB: phy-msm: Expose sysfs node to bump up USB/NOC clock rates

For some platforms USB core and NOC clocks can be run in SVS
frequency by default. Expose a DT attribute to enable the same by
selecting SVS frequency and also add a sysfs attribute to allow
users to bump up frequency to max_nominal for high performance.

Change-Id: I894b7ae653136da3ae55fdb4415e8a7858f6f2bd
Signed-off-by: Manu Gautam <mgautam@codeaurora.org>