ALSA: usb-audio: scarlett2: Improve driver startup messages

Add separate init function to call the existing controls_create
function so a custom error can be displayed if initialisation fails.

Use info level instead of error for notifications.

Display the VID/PID so device_setup is targeted to the right device.

Display "enabled" message to easily confirm that the driver is loaded.

Signed-off-by: Geoffrey D. Bennett <g@b4.vu>
Cc: <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/b5d140c65f640faf2427e085fbbc0297b32e5fce.1621584566.git.g@b4.vu


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