build: remove stale modprobe.d.5 from top-level directory

This was breaking some builds when the stale file was detected.

Signed-off-by: Jon Masters <jcm@jonmasters.org>
diff --git a/modprobe.d.5 b/modprobe.d.5
deleted file mode 100644
index d0ed026..0000000
--- a/modprobe.d.5
+++ /dev/null
@@ -1 +0,0 @@
-.so modprobe.conf.5