tests/linux: update gitignore

Signed-off-by: Barret Rhoden <brho@cs.berkeley.edu>
diff --git a/tests/linux/modules/.gitignore b/tests/linux/modules/.gitignore
index 1a86f5e..e8487a1 100644
--- a/tests/linux/modules/.gitignore
+++ b/tests/linux/modules/.gitignore
@@ -2,5 +2,6 @@
 .tmp_versions/
 Module.symvers
 *.ko
+*.mod
 *.mod.c
 modules.order