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/strider_con_defconfig b/configs/strider_con_defconfig
index 68a38e0..d6a05a8 100644
--- a/configs/strider_con_defconfig
+++ b/configs/strider_con_defconfig
@@ -19,6 +19,7 @@
 CONFIG_CMD_MMC=y
 CONFIG_CMD_I2C=y
 CONFIG_CMD_FPGAD=y
+CONFIG_CMD_PCI=y
 # CONFIG_CMD_SETEXPR is not set
 CONFIG_CMD_MII=y
 CONFIG_CMD_PING=y