ALSA: seq: Don't clear bank selection at event -> UMP MIDI2 conversion

The current code to convert from a legacy sequencer event to UMP MIDI2
clears the bank selection at each time the program change is
submitted.  This is confusing and may lead to incorrect bank values
tranmitted to the destination in the end.

Drop the line to clear the bank info and keep the provided values.

Fixes: e9e02819

 ("ALSA: seq: Automatic conversion of UMP events")
Link: https://lore.kernel.org/r/20240527151852.29036-2-tiwai@suse.de
Signed-off-by: Takashi Iwai <tiwai@suse.de>