staging: rtl8188eu: reduce indentation level in _rtw_free_sta_priv

Reduce indentation level in _rtw_free_sta_priv by returning early if
pstapriv is NULL. Also clears a line over 80 characters checkpatch
warning.

Signed-off-by: Michael Straube <straube.linux@gmail.com>
Link: https://lore.kernel.org/r/20191027130604.68379-2-straube.linux@gmail.com


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