staging: rtl8188eu: remove RT_TRACE macro

Remove RT_TRACE macro from include/rtw_debug.h, as it now has no
callers, and does not follow best practices and kernel coding
conventions.

Signed-off-by: Phillip Potter <phil@philpotter.co.uk>
Link: https://lore.kernel.org/r/20210625000756.6313-21-phil@philpotter.co.uk


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