mwifiex: kill useless list_empty checks

There's absolutely no reason to check to see if a list is empty
before iterating through it.  It's just like writing code like
this:

if (count != 0) {
  for (i = 0; i < count; i++) {
     ...
  }
}

The loop will already be avoided if "count == 0" so there was no
reason to check.

Signed-off-by: Douglas Anderson <dianders@chromium.org>
Signed-off-by: Ganapathi Bhat <gbhat@marvell.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>