staging: wlan-ng: Remove function hfa384x_dowrid_async()

Remove function hfa384x_dowrid_async as it does nothing except call
hfa384x_dowrid, and itself is called only once.
Move the contents of hfa384x_dowrid_async (i.e the call to
hfa384x_dowrid) to its call site.
Issue found with Coccinelle.

Signed-off-by: Nishka Dasgupta <nishkadg.linux@gmail.com>
Link: https://lore.kernel.org/r/20190712062807.9361-3-nishkadg.linux@gmail.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>