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_arria10_defconfig b/configs/socfpga_arria10_defconfig
index f7bcce3..0b3ec11 100644
--- a/configs/socfpga_arria10_defconfig
+++ b/configs/socfpga_arria10_defconfig
@@ -20,6 +20,7 @@
 CONFIG_CMD_CACHE=y
 CONFIG_CMD_EXT4=y
 CONFIG_CMD_EXT4_WRITE=y
+CONFIG_CMD_PART=y
 CONFIG_MTDIDS_DEFAULT="nor0=ff705000.spi.0"
 CONFIG_DOS_PARTITION=y
 # CONFIG_SPL_DOS_PARTITION is not set