tests/functional: Convert the emcraft_sf2 avocado test

A pretty straight-forward conversion of the emcraft_sf2 boot
test to the functional framework.

This was the last test that used file_truncate() in
boot_linux_console.py, so we can remove that function from that
file now, too.

Message-ID: <20241206102358.1186644-3-thuth@redhat.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>
diff --git a/MAINTAINERS b/MAINTAINERS
index 86cac83..435a87b 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -1116,6 +1116,7 @@
 S: Maintained
 F: hw/arm/msf2-som.c
 F: docs/system/arm/emcraft-sf2.rst
+F: tests/functional/test_arm_emcraft_sf2.py
 
 ASPEED BMCs
 M: Cédric Le Goater <clg@kaod.org>