block: support embedded device command line partition

Read block device partition table from command line.  The partition used
for fixed block device (eMMC) embedded device.  It is no MBR, save
storage space.  Bootloader can be easily accessed by absolute address of
data on the block device.  Users can easily change the partition.

This code reference MTD partition, source "drivers/mtd/cmdlinepart.c"
About the partition verbose reference
"Documentation/block/cmdline-partition.txt"

[akpm@linux-foundation.org: fix printk text]
[yongjun_wei@trendmicro.com.cn: fix error return code in parse_parts()]
Signed-off-by: Cai Zhiyong <caizhiyong@huawei.com>
Cc: Karel Zak <kzak@redhat.com>
Cc: "Wanglin (Albert)" <albert.wanglin@huawei.com>
Cc: Marius Groeger <mag@sysgo.de>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Brian Norris <computersforpeace@gmail.com>
Cc: Artem Bityutskiy <dedekind@infradead.org>
Signed-off-by: Wei Yongjun <yongjun_wei@trendmicro.com.cn>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/block/partitions/Kconfig b/block/partitions/Kconfig
index 4cebb2f..87a3208 100644
--- a/block/partitions/Kconfig
+++ b/block/partitions/Kconfig
@@ -260,3 +260,10 @@
 	  partition table format used by Motorola Delta machines (using
 	  sysv68).
 	  Otherwise, say N.
+
+config CMDLINE_PARTITION
+	bool "Command line partition support" if PARTITION_ADVANCED
+	select CMDLINE_PARSER
+	help
+	  Say Y here if you would read the partitions table from bootargs.
+	  The format for the command line is just like mtdparts.