Revert "net: cnss: remove redundant and dead code from platform driver"

This reverts 'commit 49350dc2 ("net: cnss: remove redundant and dead
code from platform driver")'

Backward compatibility required for the cnss export symbol. This
code change is causing compilation error in kernel rel branch during
the compilation of kernel rel with non master branch wlan driver.
Restored the old cnss export symbols to avoid the compilation
error.

CRs-Fixed: 987560
Change-Id: Iee5474a67f9ef48ce4e0dd64f3379e53ae40d7b6
Signed-off-by: Sarada Prasanna Garnayak <sgarna@codeaurora.org>