cs8900a for big endian targets

[Bob Koninckx]

Attached patch makes a number of modifications to the code to support
both big endian and little endian targets. Thoroughly tested with big
endian target (powerpc), not been tested with a little endian target as
I don't have one.

Notice that this patch supposes that the data bytes are swapped by
_hardware_ for big endian as recommended in the cs8900a datasheet

I hope that someone has the possibility to test this with a little
endian target and that it eventually makes it into the source tree.

Best,
Bob

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ir. Bob Koninckx
Katholieke Universiteit Leuven
Division Production Engineering,                   tel.  +32 16 322535
Machine Design and Automation                      fax.  +32 16 322987
Celestijnenlaan 300B                  bob.koninckx@mech.kuleuven.ac.be
B-3001 Leuven Belgium               http://www.mech.kuleuven.ac.be/pma
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