staging: r8188eu: remove DBG_88E calls from core/rtw_mlme_ext.c

Remove all DBG_88E calls from core/rtw_mlme_ext.c, including the commented
one, as they do not conform to kernel coding standards and are
superfluous. Also restructure where appropriate to remove no longer needed
code left behind by removal of these calls. This will allow the eventual
removal of the DBG_88E macro itself.

Signed-off-by: Phillip Potter <phil@philpotter.co.uk>