staging:rtl8192u: Refactor RT_RF_TYPE_DEF - Style

Rename the enumerated type RT_RF_TYPE_DEF to rt_rf_type to comply
with the coding standard, lower case type names. Removed the 'def'
postscript which provides no additional information.

The 'typedef' directive has been removed to clear the checkpatch issue
with defining new types.

The type has been moved to the file r8192U.h, where it is
actually used by the member variable 'rf_type'. Previously the member
variable used a 'u8' type so no compiler type checking is being
performed. The type has been changed to the correct type.

Signed-off-by: John Whitmore <johnfwhitmore@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>