efi_loader: non-volatile variable not deleted from file

When deleting a non-volatile variable it was deleted from memory but the
deletion was not persisted to the file system.

SetVariable() may be called with attributes == 0 to delete a variable. To
determine if the deletion shall be persisted we have to consider the
non-volatile flag in the attributes of the deleted variable and not the
value passed in the call parameter.

Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
diff --git a/lib/efi_loader/efi_variable.c b/lib/efi_loader/efi_variable.c
index a10b9ca..0c689cf 100644
--- a/lib/efi_loader/efi_variable.c
+++ b/lib/efi_loader/efi_variable.c
@@ -393,6 +393,7 @@
 
 	if (delete) {
 		/* EFI_NOT_FOUND has been handled before */
+		attributes = var->attr;
 		ret = EFI_SUCCESS;
 	} else if (append) {
 		u16 *old_data = var->name;