speaker-test: add --force-frequency option to allow hz outside range

Signed-off-by: Erik Ackermann <kurterikackermann@gmail.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
speaker-test: update man page for new -X arg, also consistency fixes

Signed-off-by: Erik Ackermann <kurterikackermann@gmail.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>