ARM: shmobile: r8a7778: add USB support

Add USB clock and EHCI, OHCI, and USB PHY platform devices for R8A7778 SoC;  add
a function to register PHY device with board-specific platform data and register
EHCI and OHCI platfrom devices from the init_late() board method.

Also,  don't forget to enable CONFIG_ARCH_HAS_[EO]HCI options for R8A7778 SoC in
Kconfig...

The patch has been tested on the BOCK-W board.

Signed-off-by: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>