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

In the Linux kernel, the following vulnerability has been resolved: 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().