seq: Simplify snd_seq_extract_output()

seq: Simplify snd_seq_extract_output()

Now that we never put UMP events on the output buffer in the legacy
mode, the check and skip of UMP events are no longer necessary.
It means that ump_allowed argument is meaningless in extract_output(),
too.

Let's drop the unnecessary check and move the code extract_output()
into snd_seq_extract_output() again, and call this directly from
snd_seq_ump_extract_output() for simplification.

Signed-off-by: Takashi Iwai <tiwai@suse.de>