selftests: usbip: remove test_bitmap noise

Remove test_bitmap noise which is a result of cut and paste error.
There is no need for this modprobe -q -r test_bitmap noise in this
test.

Signed-off-by: Shuah Khan (Samsung OSG) <shuah@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>