arm: atmel: get rid of too many ifdeffery

Get rid of too many ifdeffery in usb ohci driver

Add following two configuration for USB clock selecting
- CONFIG_USB_ATMEL_CLK_SEL_PLLB: using PLLB as usb ohci input clock
- CONFIG_USB_ATMEL_CLK_SEL_UPLL: using UPLL as usb ohci input clock

Signed-off-by: Bo Shen <voice.shen@atmel.com>
Signed-off-by: Andreas Bießmann <andreas.devel@googlemail.com>
23 files changed