i2c: designware_i2c: Don't allow changing IC_CLK

If a different input clock is required then the correct way to do this is
with a clock driver. Don't allow boards to override IC_CLK.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Heiko Schocher <hs@denx.de>

drivers/i2c/designware_i2c.h

@@ -59,9 +59,7 @@ struct i2c_regs {
 	u32 comp_type;
 };
 
-#if !defined(IC_CLK)
 #define IC_CLK			166
-#endif
 #define NANO_TO_MICRO		1000
 
 /* High and low times in different speed modes (in ns) */