rtlwifi: rtl8192de: Merge firmware routines

Merge routines fw.c and fw.h for RTL8192DE.

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