cmd: load: add load command for memory mapped

cp.b is used a lot as a way to load binaries to memory and execute
them, however we may need to integrate this with the efi subsystem to
set it up as a bootdev.

So, introduce a loadm command that will be consistent with the other
loadX commands and will call the efi API's.

ex: loadm $kernel_addr $kernel_addr_r $kernel_size

with this a kernel with CONFIG_EFI_STUB enabled will be loaded and
then subsequently booted with bootefi command.

Signed-off-by: Rui Miguel Silva <rui.silva@linaro.org>
Reviewed-by: Tom Rini <trini@konsulko.com>

include/efi_loader.h

@@ -591,6 +591,8 @@ efi_status_t efi_load_pe(struct efi_loaded_image_obj *handle,
 void efi_save_gd(void);
 /* Call this to relocate the runtime section to an address space */
 void efi_runtime_relocate(ulong offset, struct efi_mem_desc *map);
+/* Call this to get image parameters */
+void efi_get_image_parameters(void **img_addr, size_t *img_size);
 /* Add a new object to the object list. */
 void efi_add_handle(efi_handle_t obj);
 /* Create handle */