rtlwifi: rtl8192de: Fix firmware initialization

Before the switch to asynchronous firmware loading (mainline commit b0302ab),
it was necessary to load firmware when initializing the first of the units
in a dual-mac system. After the change, it is necessary to load firmware in
both units.

Signed-off-by: Larry Finger <Larry.Finger@lwfinger.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>