ARM: at91: move sam9n12 SoC to the CCF

This patch removes the selection of AT91_USE_OLD_CLK when selecting
sam9n12 SoC support. This will automatically enable COMMON_CLK_AT91 option
and add support for at91 common clk implementation.
Signed-off-by: Boris BREZILLON <boris.brezillon@free-electrons.com>
Tested-by: Bo Shen <voice.shen@atmel.com>
Signed-off-by: Nicolas Ferre <nicolas.ferre@atmel.com>

arch/arm/mach-at91/Kconfig

@@ -182,7 +182,6 @@ config SOC_AT91SAM9N12
 	select HAVE_AT91_DBGU0
 	select HAVE_FB_ATMEL
 	select SOC_AT91SAM9
-	select AT91_USE_OLD_CLK
 	select HAVE_AT91_USB_CLK
 	help
 	  Select this if you are using Atmel's AT91SAM9N12 SoC.