Checking d_class in dump_info leads to lengthy conditionals so let's
shorten things a bit by introducing a helper function.

Signed-off-by: Janosch Frank <frankja@linux.ibm.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Message-Id: <20220330123603.107120-7-frankja@linux.ibm.com>