tests/qtest/libqtest.h: Remove stray space from doc comment

The doc comment for qtest_cb_for_every_machine has a stray
space at the start of its description, which makes kernel-doc
think that this line is part of the documentation of the
skip_old_versioned argument. The result is that the HTML
doesn't have a "Description" section and the text is instead
put in the wrong place.

Remove the stray space.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Message-id: 20250814171324.1614516-3-peter.maydell@linaro.org

tests/qtest/libqtest.h

@@ -977,7 +977,7 @@ void qtest_qmp_fds_assert_success(QTestState *qts, int *fds, size_t nfds,
  * @cb: Pointer to the callback function
  * @skip_old_versioned: true if versioned old machine types should be skipped
  *
- *  Call a callback function for every name of all available machines.
+ * Call a callback function for every name of all available machines.
  */
 void qtest_cb_for_every_machine(void (*cb)(const char *machine),
                                 bool skip_old_versioned);