cnss2: Add a module parameter for handling firmware waltest

Add a module parameter to handle firmware waltest that directly
return after QMI handshake if waltest is enabled. This can give
the flexibility to do firmware waltest in pre-silicon stage
development.

Change-Id: I05dee19b06c08fa4d52681822b11d3c2ac90ae7d
Signed-off-by: Yue Ma <yuem@codeaurora.org>