efi_loader: Support loading a ramdisk with bootefi

It is sometimes useful to be able to boot via EFI using a ramdisk. Add
support for this.

Fix a 'specifiy' typo while here.

Series-to: heinrich
Fixes: #8

cmd/bootefi.c

@@ -232,7 +232,7 @@ static int do_bootefi(struct cmd_tbl *cmdtp, int flag, int argc,
 }
 
 U_BOOT_LONGHELP(bootefi,
-	"<image address>[:<image size>] [<ramdisk_address>:<size>] [<fdt address>]\n"
+	"<image address>[:<image size>] [<ramdisk_address>:<size> | -] [<fdt address>]\n"
 	"  - boot EFI payload\n"
 #ifdef CONFIG_CMD_BOOTEFI_HELLO
 	"bootefi hello\n"

doc/usage/cmd/bootefi.rst

@@ -12,7 +12,7 @@ Synopsis
 
 ::
 
-    bootefi <image_addr>[:<image_size>] [<ramdisk_addr>] [<fdt_addr>]
+    bootefi <image_addr>[:<image_size>] [<ramdisk_addr> | -] [<fdt_addr>]
     bootefi bootmgr [<fdt_addr>]
     bootefi hello [<fdt_addr>]
     bootefi selftest [<fdt_addr>]