rtl8188eu: Remove a few more W=1 warnings

Signed-off-by: Larry Finger <Larry.Finger@lwfinger.net>
rtl8188eu: Remove dead code inside "ifdef PLATFORM_FREEBSD" sections

Signed-off-by: Larry Finger <Larry.Finger@lwfinger.net>
rtl8188eu: Remove dead code used for PLATFORM_WINDOWS, PLATFORM_OS_XP, and PLATFORM_OS_CE

Signed-off-by: Larry Finger <Larry.Finger@lwfinger.net>
rtl8188eu: Remove dead code for other PLATFORM_XX variables

Signed-off-by: Larry Finger <Larry.Finger@lwfinger.net>
rtl8199eu: Remove all PLATFORM_LINUX ifdefs

This option is always chosen.

Signed-off-by: Larry Finger <Larry.Finger@lwfinger.net>
rtl8188eu: Remove configuration parameters and dead code for other devices

The vendor code includes some code that is needed for RTL8182CU, RTL8192DU,
RTL8711, RTL8712, and RTL8723AU. This dead code is removed.

Signed-off-by: Larry Finger <Larry.Finger@lwfinger.net>