i2c-bfin-twi: Just let i2c-bfin-twi driver depends on BLACKFIN

Simply use "depends on BLACKFIN" (which is technically correct) and just
document which machines have the device.
Signed-off-by: Bryan Wu <cooloney@kernel.org>
Signed-off-by: Jean Delvare <khali@linux-fr.org>

drivers/i2c/busses/Kconfig

@@ -100,9 +100,12 @@ config I2C_AU1550
 
 config I2C_BLACKFIN_TWI
 	tristate "Blackfin TWI I2C support"
-	depends on BF534 || BF536 || BF537 || BF54x
+	depends on BLACKFIN
 	help
-	  This is the TWI I2C device driver for Blackfin 534/536/537/54x.
+	  This is the TWI I2C device driver for Blackfin BF522, BF525,
+	  BF527, BF534, BF536, BF537 and BF54x. For other Blackfin processors,
+	  please don't use this driver.
+
 	  This driver can also be built as a module.  If so, the module
 	  will be called i2c-bfin-twi.