mfd: Add anatop mfd driver

Signed-off-by: Ying-Chun Liu (PaulLiu) <paul.liu@linaro.org>
Acked-by: Shawn Guo <shawn.guo@linaro.org>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Cc: Venu Byravarasu <vbyravarasu@nvidia.com>
Cc: Peter Korsgaard <jacmet@sunsite.dk>
Cc: Rob Lee <rob.lee@linaro.org>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>