efi_loader: correct a definition of struct efi_capsule_header

See UEFI specification, section 8.5.3.
In addition, the structure, efi_capsule_header, should be "packed"
as it is a serialized binary format in a capsule file.

Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>
diff --git a/include/efi_api.h b/include/efi_api.h
index 3b0845a..4713da2 100644
--- a/include/efi_api.h
+++ b/include/efi_api.h
@@ -217,11 +217,11 @@
 #define CAPSULE_FLAGS_INITIATE_RESET		0x00040000
 
 struct efi_capsule_header {
-	efi_guid_t *capsule_guid;
+	efi_guid_t capsule_guid;
 	u32 header_size;
 	u32 flags;
 	u32 capsule_image_size;
-};
+} __packed;
 
 #define EFI_RT_SUPPORTED_GET_TIME			0x0001
 #define EFI_RT_SUPPORTED_SET_TIME			0x0002