Revert "at91: clock: remove chip macro for plla div2."

The bit 12 of mckr in at91sam9g20 is used for processor clock divisor
while not like at91sam9g45/9m10g45, at91sam9n12, at91sam9x5 used for
PLLA divisor

So commit fe1d568 (at91: clock: remove chip macro for plla div2)
will cause error operation on at91sam9g20

Signed-off-by: Bo Shen <voice.shen@atmel.com>
ARM: at91/clock: at91sam9n12 has PLLA divisor by 2

The at91sam9n12 has PLLA divisor by 2, add it

Signed-off-by: Bo Shen <voice.shen@atmel.com>
USB: ohci-at91: add clock select to avoid more #ifdeffery

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>
ARM: at91: using micro to calculate divisor

Using micro to calculate divisor

Add AT91_PMC_USBS_USB_PLLB definition

Signed-off-by: Bo Shen <voice.shen@atmel.com>
USB: ohci-at91: at91sam9n12 use PMC_USB for usb clock divisor

at91sam9n12 using PLLB as usb input clock, however it use usb clock
register (PMC_USB) for usb clock divisor, others include usb clock
divisor into PLLB register (bit 29 - 28)

Signed-off-by: Bo Shen <voice.shen@atmel.com>
ARM: at91sam9n12: add usb ohci host support

Add usb ohci host support for at91sam9n12ek board

Signed-off-by: Bo Shen <voice.shen@atmel.com>
USB: ohci-at91: make OHCI work on at91sam9g10 SoC

The at91sam9g10 need configure HCK0 to make OHCI work

Signed-off-by: Bo Shen <voice.shen@atmel.com>
ARM: at91sam9g45: fix typo for OHCI

fix typo for OHCI

Signed-off-by: Bo Shen <voice.shen@atmel.com>