selftests/hid: Add host-tools to .gitignore

When compiling these selftests the host-tools directory is generated.
Add it to the .gitignore so git doesn't see these files as trackable.

Signed-off-by: Charlie Jenkins <charlie@rivosinc.com>
Signed-off-by: Jiri Kosina <jkosina@suse.com>

Author: charlie-rivos

tools/testing/selftests/hid/.gitignore

@@ -1,5 +1,6 @@
 bpftool
 *.skel.h
+/host-tools
 /tools
 hid_bpf
 hidraw