i2c: designware: Make dw_readl() and dw_writel() static

dw_readl() and dw_writel() are not used outside of i2c-designware-core and
they are not exported so make them static and remove their forward
declaration.

Signed-off-by: Jarkko Nikula <jarkko.nikula@linux.intel.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
diff --git a/drivers/i2c/busses/i2c-designware-core.c b/drivers/i2c/busses/i2c-designware-core.c
index c9e93a7..52272a0 100644
--- a/drivers/i2c/busses/i2c-designware-core.c
+++ b/drivers/i2c/busses/i2c-designware-core.c
@@ -165,7 +165,7 @@
 		"lost arbitration",
 };
 
-u32 dw_readl(struct dw_i2c_dev *dev, int offset)
+static u32 dw_readl(struct dw_i2c_dev *dev, int offset)
 {
 	u32 value;
 
@@ -181,7 +181,7 @@
 		return value;
 }
 
-void dw_writel(struct dw_i2c_dev *dev, u32 b, int offset)
+static void dw_writel(struct dw_i2c_dev *dev, u32 b, int offset)
 {
 	if (dev->accessor_flags & ACCESS_SWAP)
 		b = swab32(b);