ASoC: Intel: avs: Allow for dumping FW_REGS area

SRAM0 window begins with a block of memory, usually of size PAGE_SIZE,
dedicated to the base firmware registers. When debugging firmware, it is
desirable to be able to dump them at will.

Signed-off-by: Cezary Rojewski <cezary.rojewski@intel.com>
Link: https://lore.kernel.org/r/20221202152841.672536-16-cezary.rojewski@intel.com
Signed-off-by: Mark Brown <broonie@kernel.org>