drivers: marvell: comphy-a3700: Set TXDCLK_2X_SEL bit during PCIe initialization

Marvell Armada 3700 Functional Specifications, section 52.2 PCIe Link
Initialization says that TXDCLK_2X_SEL bit needs to be enabled for PCIe
Root Complex mode. Both U-Boot and Linux kernel support only Root Complex
mode. Set this bit.

Signed-off-by: Pali Rohár <pali@kernel.org>
Change-Id: Id2a538c379b911b62597f9463b4842b7b5c24df7
diff --git a/drivers/marvell/comphy/phy-comphy-3700.h b/drivers/marvell/comphy/phy-comphy-3700.h
index 1628e36..94056f1 100644
--- a/drivers/marvell/comphy/phy-comphy-3700.h
+++ b/drivers/marvell/comphy/phy-comphy-3700.h
@@ -104,6 +104,7 @@
 #define COMPHY_MISC_REG0_ADDR		0x4F
 #define MISC_REG0_ADDR(unit)		(COMPHY_MISC_REG0_ADDR * PHY_SHFT(unit))
 #define CLK100M_125M_EN			BIT(4)
+#define TXDCLK_2X_SEL			BIT(6)
 #define CLK500M_EN			BIT(7)
 #define PHY_REF_CLK_SEL			BIT(10)
 #define MISC_REG0_DEFAULT_VALUE		0xA00D