media: ddbridge: split code into multiple files

media: ddbridge: split code into multiple files

As of 0.9.9b, the ddbridge code has been split from one single file
(ddbridge-core.c) into multiple files, with the purpose of taking care of
different topics, and to be able to reuse code in different kernel modules
(ddbridge.ko and octonet.ko). This applies the same code split, with a
notable difference:

In the vendor package, the split was done by moving all code parts into
separate files, and in the "main" code files (ddbridge.c and octonet.c),
a simple "#include ddbridge-core.c" was done.

In this patch, the same split (codewise) is done, but all resulting .c/.o
files will be handled by the makefile, with proper prototyping of all
shared functions done in ddbridge.h. To avoid conflicts wrt the global
space, the I2C functions and necessary prototypes for ddbridge-i2c.c are
moved into ddbridge-i2c.h, which is to be included wherever required.

Signed-off-by: Daniel Scheller <d.scheller@gmx.net>
Tested-by: Richard Scobie <r.scobie@clear.net.nz>
Tested-by: Jasmin Jessich <jasmin@anw.at>
Tested-by: Dietmar Spingler <d_spingler@freenet.de>
Tested-by: Manfred Knick <Manfred.Knick@t-online.de>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>