i2c-designware: Allow mixed endianness accesses

Allows CPUs of a given endianness to access a dw controller of a different
endianness. Endianncess difference is detected at run time through the dw
component type register.

Signed-off-by: Jean-Hugues Deschenes <jean-hugues.deschenes@octasic.com>
Signed-off-by: Dirk Brandewie <dirk.brandewie@gmail.com>
Signed-off-by: Ben Dooks <ben-linux@fluff.org>