efi_loader: Increase path string to 32 characters

Whenever we want to tell our payload about a path, we limit ourselves
to a reasonable amount of characters. So far we only passed in device
names - exceeding 16 chars was unlikely there.

However by now we also pass real file path information, so let's increase
the limit to 32 characters. That way common paths like "boot/efi/bootaa64.efi"
fit just fine.

Signed-off-by: Alexander Graf <agraf@suse.de>
diff --git a/include/efi_api.h b/include/efi_api.h
index 6960448..51d7586 100644
--- a/include/efi_api.h
+++ b/include/efi_api.h
@@ -259,7 +259,7 @@
 
 struct efi_device_path_file_path {
 	struct efi_device_path dp;
-	u16 str[16];
+	u16 str[32];
 };
 
 #define BLOCK_IO_GUID \