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/MPC8572DS_36BIT_defconfig b/configs/MPC8572DS_36BIT_defconfig
index 673d7ce..ad6c307 100644
--- a/configs/MPC8572DS_36BIT_defconfig
+++ b/configs/MPC8572DS_36BIT_defconfig
@@ -12,6 +12,7 @@
 CONFIG_HUSH_PARSER=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