The PCM3008 is used on the Lyrtech SFFSDR board, in conjunction with an
FPGA that generates the bit clock and the master clock

[Downgraded the rate debug print to pr_debug() in hw_params, converted
asm/gpio.h to linux/gpio.h -- broonie]
Signed-off-by: NHugo Villeneuve <hugo@hugovil.com>
Signed-off-by: NMark Brown <broonie@opensource.wolfsonmicro.com>