arm/km: speed up i2c access for keymile boards

We don't need 3us delay for our i2c bus. Decrease it to 1us.
It would also be possible to use 100ns in the future, but
currently kirkwood has no ndelay implementation.
Signed-off-by: NHolger Brunck <holger.brunck@keymile.com>
Cc: Valentin Longchamp <valentin.longchamp@keymile.com>
Cc: Prafulla Wadaskar <prafulla@marvell.com>
Cc: Heiko Schocher <hs@denx.de>
Acked-by: NHeiko Schocher <hs@denx.de>

include/configs/km/km_arm.h

@@ -194,7 +194,7 @@ int get_scl(void);
 #define I2C_SCL(bit)	kw_gpio_set_value(KM_KIRKWOOD_SCL_PIN, bit)
 #endif
 
-#define I2C_DELAY	udelay(3)	/* 1/4 I2C clock duration */
+#define I2C_DELAY	udelay(1)
 #define I2C_SOFT_DECLARATIONS
 
 #endif