cnss2: Make sure RAM dump is cleaned during SSR powerup

Currently firmware RAM dump will be only cleaned when ramdump
callback is invoked by SSR framework. There are cases that
do_ramdump is disabled from SSR framework, so the callback will
never come. Make sure RAM dump is cleaned during SSR powerup if
it's not cleaned before to avoid confusing MHI driver.

Change-Id: I4c85d3f39a5bff4ec85d3abf931a194a51708b97
Signed-off-by: Yue Ma <yuem@codeaurora.org>