Convert CONFIG_PCIE_IMX to Kconfig

This converts the following to Kconfig:
   CONFIG_PCIE_IMX

Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/configs/mx6sabresd_defconfig b/configs/mx6sabresd_defconfig
index 15dbaf8..f5ad366 100644
--- a/configs/mx6sabresd_defconfig
+++ b/configs/mx6sabresd_defconfig
@@ -97,6 +97,7 @@
 CONFIG_RGMII=y
 CONFIG_MII=y
 CONFIG_PCI=y
+CONFIG_PCIE_IMX=y
 CONFIG_PINCTRL=y
 CONFIG_PINCTRL_IMX6=y
 CONFIG_POWER_LEGACY=y