fix dh_auto_clean

1 job for debian/master in 5 minutes and 50 seconds (queued for 3 seconds)
Status Job ID Name Coverage
  Test
failed #162535
build

00:05:50

 
Name Stage Failure
failed
build Test
dh_auto_build: invalid or non-existing path to the source directory: toboot
make[1]: *** [debian/rules:7: override_dh_auto_build] Error 2
make[1]: Leaving directory '/builds/debian/firmware-tomu'
make: *** [debian/rules:4: build] Error 2
dpkg-buildpackage: error: debian/rules build subprocess returned exit status 2
debuild: fatal error at line 1182:
dpkg-buildpackage -us -uc -ui -i -I failed
gbp:error: 'debuild -i -I -uc -us' failed: it exited with 29
ERROR: Job failed: exit code 1