fix(mt8186): move SSPM base register definition to platform_def.h

- move base register definition to platform_def.h for maintenance.
- SSPM_MBOX_3_BASE is redefined, use SSPM_MBOX_BASE instead.

Signed-off-by: Yidi Lin <yidilin@chromium.org>
Change-Id: Ibb0291ce7b7426068392e90bd70f29d1a90d5297
3 files changed