ARM: socfpga: Enable part command for socfpga platform

Enable CONFIG_CMD_PART item, as default environment requires it
and complains this command in unknown.

Signed-off-by: Andrey Zhizhikin <andrey.z@gmail.com>
diff --git a/configs/socfpga_de10_nano_defconfig b/configs/socfpga_de10_nano_defconfig
index ecf6de3..17780af 100644
--- a/configs/socfpga_de10_nano_defconfig
+++ b/configs/socfpga_de10_nano_defconfig
@@ -34,6 +34,7 @@
 CONFIG_CMD_EXT4_WRITE=y
 CONFIG_CMD_FAT=y
 CONFIG_CMD_FS_GENERIC=y
+CONFIG_CMD_PART=y
 CONFIG_MTDIDS_DEFAULT="nor0=ff705000.spi.0"
 CONFIG_ENV_IS_IN_MMC=y
 CONFIG_SPL_DM=y