mfd: mfd_cell is now implicitly available to mc13xxx drivers

The cell's platform_data is now accessed with a helper function;
change clients to use that, and remove the now-unused data_size.

Note that mfd-core no longer makes a copy of platform_data, but the
mc13xxx-core driver creates the pdata structures on the stack.  In
order to get around that, the various ARM mach types that set the
pdata have been changed to hold the variable in static (global) memory.
Also note that __initdata references in aforementioned pdata structs
have been dropped.

Signed-off-by: Andres Salomon <dilinger@queued.net>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>