ALSA: firewire-motu: add bounds check in put_user loop for DSP events

ALSA: firewire-motu: add bounds check in put_user loop for DSP events

In the DSP event handling code, a put_user() loop copies event data.
When the user buffer size is not aligned to 4 bytes, it could overwrite
beyond the buffer boundary.

Fix by adding a bounds check before put_user().

Suggested-by: Takashi Iwai <tiwai@suse.de>
Fixes: 634ec0b2906e ("ALSA: firewire-motu: notify event for parameter change in register DSP model")
Signed-off-by: Junrui Luo <moonafterrain@outlook.com>
Link: https://patch.msgid.link/SYBPR01MB788112C72AF8A1C8C448B4B8AFA3A@SYBPR01MB7881.ausprd01.prod.outlook.com
Signed-off-by: Takashi Iwai <tiwai@suse.de>