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/sbc8641d_defconfig b/configs/sbc8641d_defconfig
index 7174e00..6bb2ed6 100644
--- a/configs/sbc8641d_defconfig
+++ b/configs/sbc8641d_defconfig
@@ -7,6 +7,7 @@
 # CONFIG_DISPLAY_BOARDINFO is not set
 CONFIG_HUSH_PARSER=y
 CONFIG_CMD_I2C=y
+CONFIG_CMD_PCI=y
 # CONFIG_CMD_SETEXPR is not set
 CONFIG_CMD_PING=y
 CONFIG_DOS_PARTITION=y