efi_loader: UninstallMultipleProtocolInterfaces error code

If UninstallMultipleProtocolInterfaces fails, we sometimes return the wrong
status code. The UEFI spec mandates to always return EFI_INVALID_PARAMETER.

Update unit test.

Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
Signed-off-by: Alexander Graf <agraf@suse.de>
diff --git a/lib/efi_loader/efi_boottime.c b/lib/efi_loader/efi_boottime.c
index e3d911f..eb652e8 100644
--- a/lib/efi_loader/efi_boottime.c
+++ b/lib/efi_loader/efi_boottime.c
@@ -2414,7 +2414,8 @@
 	}
 	efi_va_end(argptr);
 
-	return EFI_EXIT(r);
+	/* In case of an error always return EFI_INVALID_PARAMETER */
+	return EFI_EXIT(EFI_INVALID_PARAMETER);
 }
 
 /**