ASoC: wcd934x: WDSP debug enhancement

Add interface to trigger WDSP dumps for debug use.
Important register dump and WDSP ramdump are both collected when
DEBUG_DUMP string is sent from userspace via WDSP misc node or
when WDSP boot timeout happens.

CRs-Fixed: 2117755
Change-Id: I8b91a8939201a54512a5e3557ce771b4ff2ff075
Signed-off-by: Walter Yang <yandongy@codeaurora.org>