rme: initial implementation of a function to read mixer values from the device flash.  This is not used yet and has only been compile tested at this stage.  RME documentation relating to the mixer flash has also been updated.

git-svn-id: svn+ssh://ffado.org/ffado/trunk@2278 2be59082-3212-0410-8809-b0798e1608f0
rme: deal with ff800 flash sector blocks within read_flash() and write_flash().  Callers therefore don't need to be concerned with keeping their request sizes under that of a sector.

git-svn-id: svn+ssh://ffado.org/ffado/trunk@2279 2be59082-3212-0410-8809-b0798e1608f0
rme: first cut at writing to the mixer flash.  Compile tested only at this stage.

git-svn-id: svn+ssh://ffado.org/ffado/trunk@2280 2be59082-3212-0410-8809-b0798e1608f0
rme: refactor flash value calculations to remove code duplication.  Fix some indexing errors when accessing the flash arrays.

git-svn-id: svn+ssh://ffado.org/ffado/trunk@2281 2be59082-3212-0410-8809-b0798e1608f0
rme: revert some erroneous byte swapping left over from testing which accidently made its way into r2281.

git-svn-id: svn+ssh://ffado.org/ffado/trunk@2282 2be59082-3212-0410-8809-b0798e1608f0