arm, am33xx: add clk_get prototype

the clk_get() function is needed for the da8xx-fb video driver,
which is used on the am3xx based siemens boards.

Signed-off-by: Heiko Schocher <hs@denx.de>
Cc: Tom Rini <trini@ti.com>
Acked-by: Tom Rini <trini@ti.com>

arch/arm/include/asm/arch-am33xx/hardware.h

@@ -78,4 +78,5 @@
 #define USB0_OTG_BASE			0x47401000
 #define USB1_OTG_BASE			0x47401800
 
+int clk_get(int clk);
 #endif /* __AM33XX_HARDWARE_H */