Convert CONFIG_CMD_PCI to Kconfig

This converts the following to Kconfig:
   CONFIG_CMD_PCI

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Philipp Tomsich <philipp.tomsich@theobroma-systems.com>
diff --git a/configs/TWR-P1025_defconfig b/configs/TWR-P1025_defconfig
index e32a060..639ac2a 100644
--- a/configs/TWR-P1025_defconfig
+++ b/configs/TWR-P1025_defconfig
@@ -15,6 +15,7 @@
 CONFIG_CMD_MMC=y
 CONFIG_CMD_I2C=y
 CONFIG_CMD_USB=y
+CONFIG_CMD_PCI=y
 CONFIG_CMD_MII=y
 CONFIG_CMD_PING=y
 # CONFIG_CMD_HASH is not set