ASoC: soc-cache: Add support for default readable()/volatile() functions

ASoC: soc-cache: Add support for default readable()/volatile() functions

For common scenarios, device drivers can provide a table of all the
registers that are at least either readable/writable/volatile.  The idea
is that if a register lookup fails, all of its read/write/vol members
will be zero and will be treated as default.  This also reduces the
size of the register access array.

Signed-off-by: Dimitris Papastamos <[email protected]>
Acked-by: Liam Girdwood <[email protected]>
Signed-off-by: Mark Brown <[email protected]>