efi_selftest: SNP unit test on sandbox

Running the simple network protocol test on the sandbox requires setting
the environment variable ethact to a network interface connected to a DHCP
server and ethrotate to 'no'. So let's make it an on-request test on the
sandbox (selectable by setting environment variable efi_selftest).

Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
Signed-off-by: Alexander Graf <agraf@suse.de>
diff --git a/lib/efi_selftest/efi_selftest_snp.c b/lib/efi_selftest/efi_selftest_snp.c
index e10a34b..f1e23c4 100644
--- a/lib/efi_selftest/efi_selftest_snp.c
+++ b/lib/efi_selftest/efi_selftest_snp.c
@@ -427,4 +427,12 @@
 	.setup = setup,
 	.execute = execute,
 	.teardown = teardown,
+#ifdef CONFIG_SANDBOX
+	/*
+	 * Running this test on the sandbox requires setting environment
+	 * variable ethact to a network interface connected to a DHCP server and
+	 * ethrotate to 'no'.
+	 */
+	.on_request = true,
+#endif
 };