mfd: Add marimba Core driver

Marimba driver supports adding Marimba slave
devices(FM, Codec and TSADC) as sub devices
to the Marimba Core. Provides interface to
read/write registers using I2C to access the
registers on the Top level and subdevices.

It also adds ssbi-client driver intialization
to access registers of TSADC which is part of
marimba and accessed through SSBI. Provides
interface to read/write registers of the
sub-device over SSBI.

Acked-by: Siddartha Mohanadoss <smohanad@qualcomm.com>
Signed-off-by: Bryan Huntsman <bryanh@quicinc.com>