[ALSA] ASoC: Add WM8510 driver

The WM8510 is a mono CODEC with speaker driver optimised for telephony
applications, featuring:
 - 16/20/24/32 bit audio at data rates between 8kHz and 48kHz
 - On-chip PLL
 - Dual microphone inputs

This driver was originally written by Liam Girdwood with updates from
Brett Saunders, Geoffrey Wossum and myself.

Signed-off-by: Liam Girdwood <lg@opensource.wolfsonmicro.com>
Signed-off-by: Brett Saunders <breton.saunders@ntlworld.com>
Signed-off-by: Geoffrey Wossum <geoffrey@pager.net>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>