build: docker: scripts: autotools: do not fail if .m2/ exists

Previously, when doing manual runs inside of the docker container,
the `autotools.sh` script would fail if the `.m2/` directory already
existed. This was a minor annoyance.

Simply pass the `-p` flag to `mkdir`.

Signed-off-by: Chris Friedt <cfriedt@meta.com>
diff --git a/build/docker/scripts/autotools.sh b/build/docker/scripts/autotools.sh
index 52b17ee..c92599f 100755
--- a/build/docker/scripts/autotools.sh
+++ b/build/docker/scripts/autotools.sh
@@ -1,7 +1,7 @@
 #!/bin/sh
 set -ev
 
-mkdir ~/.m2
+mkdir -p ~/.m2
 tee >~/.m2/settings.xml <<EOF
 <settings xmlns='http://maven.apache.org/SETTINGS/1.0.0'>
   <mirrors>