mfd: tmio_mmc hardware abstraction for CNF area

This patch abstracts out the CNF area code from tmio_mmc which
is not present in all hardware that can use this driver. This
is required so that we can support non-toshiba based hardware.

ASIC3 support by Philipp Zabel

Signed-off-by: Ian Molton <ian@mnementh.co.uk>
Signed-off-by: Magnus Damm <damm@opensource.se>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>