BOOT: Add RAW ramdisk support to bootz

This patch allows loading RAW ramdisk via bootz command. The raw ramdisk is
loaded only in case it's size is specified:

  bootz <kernel addr> <ramdisk addr>:<ramdisk size> <fdt addr>

For example:

  bootz 0x42000000 0x43000000:0x12345 0x44000000

Signed-off-by: Marek Vasut <marex@denx.de>
Signed-off-by: Rob Herring <rob.herring@calxeda.com>
Cc: Tom Warren <TWarren@nvidia.com>
Cc: albert.u.boot@aribaud.net
Cc: afleming@gmail.com
Cc: Simon Glass <sjg@chromium.org>
Cc: Stephen Warren <swarren@nvidia.com>
Cc: Nicolas Pitre <nico@fluxnic.net>
Cc: Wolfgang Denk <wd@denx.de>
Cc: Detlev Zundel <dzu@denx.de>
diff --git a/common/cmd_bootm.c b/common/cmd_bootm.c
index 5e5d572..9ad2535 100644
--- a/common/cmd_bootm.c
+++ b/common/cmd_bootm.c
@@ -1629,9 +1629,11 @@
 U_BOOT_CMD(
 	bootz,	CONFIG_SYS_MAXARGS,	1,	do_bootz,
 	"boot Linux zImage image from memory",
-	"[addr [initrd] [fdt]]\n    - boot Linux zImage stored in memory\n"
+	"[addr [initrd[:size]] [fdt]]\n"
+	"    - boot Linux zImage stored in memory\n"
 	"\tThe argument 'initrd' is optional and specifies the address\n"
-	"\tof the initrd in memory.\n"
+	"\tof the initrd in memory. The optional argument ':size' allows\n"
+	"\tspecifying the size of RAW initrd.\n"
 #if defined(CONFIG_OF_LIBFDT)
 	"\tWhen booting a Linux kernel which requires a flat device-tree\n"
 	"\ta third argument is required which is the address of the\n"