ALSA: usb-audio: add dB range mapping for some devices

Add the correct dB ranges of Bose Companion 5 and Drangonfly DAC 1.2.

Signed-off-by: Yao-Wen Mao <yaowen@google.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>