efi_loader: fix hii keyboard layout pointer computation

The EFI_HII_KEYBOARD_LAYOUT field `layout_length' is expressed in bytes,
but we add it to the `layout' pointer with (scaled) pointer arithmetic.
When adding an HII keyboard package with multiple keyboard layouts, this
results in only the first layout being added correctly; fix it.

Fixes: 8d3b77e36e ("efi: hii: add keyboard layout package support")
Signed-off-by: Vincent Stehlé <vincent.stehle@arm.com>
Cc: Heinrich Schuchardt <xypron.glpk@gmx.de>
Cc: Ilias Apalodimas <ilias.apalodimas@linaro.org>
Cc: Tom Rini <trini@konsulko.com>
Cc: AKASHI Takahiro <akashi.tkhro@gmail.com>

lib/efi_loader/efi_hii.c

@@ -324,7 +324,8 @@ add_keyboard_package(struct efi_hii_packagelist *hii,
 		list_add_tail(&layout_data->link_sys,
 			      &efi_keyboard_layout_list);
 
-		layout += layout_length;
+		layout = (struct efi_hii_keyboard_layout *)
+			 ((uintptr_t)layout + layout_length);
 	}
 
 	list_add_tail(&package_data->link, &hii->keyboard_packages);