ALSA: usb-audio: scarlett2: Coding style improvements

Improve alignment and readability with:
- Whitespace fixes
- Add leading zeros to 32-bit flag values
- Rename SCARLETT2_USB_GET_METER_LEVELS to SCARLETT2_USB_GET_METER
- Rename SCARLETT2_PORT_DIRECTIONS to SCARLETT2_PORT_DIRNS

Signed-off-by: Geoffrey D. Bennett <g@b4.vu>
Link: https://lore.kernel.org/r/20210620164628.GA9172@m.b4.vu


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