ARM: davinci: da8xx: add new USB PHY clock init using common clock framework

This adds the new USB PHY clock init in mach-davinci/usb-da8xx.c using
the new common clock framework drivers.

The #ifdefs are needed to prevent compile errors until the entire
ARCH_DAVINCI is converted.

Signed-off-by: David Lechner <david@lechnology.com>
Signed-off-by: Sekhar Nori <nsekhar@ti.com>