cmd_part: add partition-related command

This implements the following:

part uuid mmc 0:1
  -> print partition UUID
part uuid mmc 0:1 uuid
  -> set environment variable to partition UUID
part list mmc 0
  -> list the partitions on the specified device

"part uuid" can be useful when writing a bootcmd which searches all
known devices for something bootable, and then wants the kernel to
use the same partition as the root device, e.g.:

part uuid ${devtype} ${devnum}:${rootpart} uuid
setenv bootargs root=PARTUUID=${uuid} ...

Signed-off-by: Stephen Warren <swarren@nvidia.com>
diff --git a/common/Makefile b/common/Makefile
index 482795e..b56df1d 100644
--- a/common/Makefile
+++ b/common/Makefile
@@ -136,6 +136,7 @@
 COBJS-$(CONFIG_CMD_NET) += cmd_net.o
 COBJS-$(CONFIG_CMD_ONENAND) += cmd_onenand.o
 COBJS-$(CONFIG_CMD_OTP) += cmd_otp.o
+COBJS-$(CONFIG_CMD_PART) += cmd_part.o
 ifdef CONFIG_PCI
 COBJS-$(CONFIG_CMD_PCI) += cmd_pci.o
 endif