AM35xx: Add clock support for new modules on AM35xx

This patch adds clock support for the following AM35xx modules
	- Ethernet MAC
	- CAN Controller (HECC)
	- New MUSB OTG Controller with integrated Phy
	- Video Processing Front End (VPFE)
	- Additional UART (UART4)

Signed-off-by: Ranjith Lohithakshan <ranjithl@ti.com>
Signed-off-by: Paul Walmsley <paul@pwsan.com>