clk: at91: add PMC usb clock

This patch adds new at91 usb clock implementation using common clk framework.
This clock is used to clock usb ports (ohci, ehci and udc).

Signed-off-by: Boris BREZILLON <b.brezillon@overkiz.com>
Acked-by: Mike Turquette <mturquette@linaro.org>
Signed-off-by: Nicolas Ferre <nicolas.ferre@atmel.com>
diff --git a/drivers/clk/at91/Makefile b/drivers/clk/at91/Makefile
index a824883..61db058 100644
--- a/drivers/clk/at91/Makefile
+++ b/drivers/clk/at91/Makefile
@@ -8,3 +8,4 @@
 
 obj-$(CONFIG_AT91_PROGRAMMABLE_CLOCKS)	+= clk-programmable.o
 obj-$(CONFIG_HAVE_AT91_UTMI)		+= clk-utmi.o
+obj-$(CONFIG_HAVE_AT91_USB_CLK)		+= clk-usb.o