blackfin: add spi and i2c specific get clock functions

Signed-off-by: Sonic Zhang <sonic.zhang@analog.com>
diff --git a/drivers/i2c/bfin-twi_i2c.c b/drivers/i2c/bfin-twi_i2c.c
index 5c37280..cfab064 100644
--- a/drivers/i2c/bfin-twi_i2c.c
+++ b/drivers/i2c/bfin-twi_i2c.c
@@ -10,6 +10,7 @@
 #include <i2c.h>
 
 #include <asm/blackfin.h>
+#include <asm/clock.h>
 #include <asm/mach-common/bits/twi.h>
 
 /* Every register is 32bit aligned, but only 16bits in size */
@@ -274,7 +275,7 @@
  */
 void i2c_init(int speed, int slaveaddr)
 {
-	uint8_t prescale = ((get_sclk() / 1000 / 1000 + 5) / 10) & 0x7F;
+	uint8_t prescale = ((get_i2c_clk() / 1000 / 1000 + 5) / 10) & 0x7F;
 
 	/* Set TWI internal clock as 10MHz */
 	twi->control = prescale;