m68k: disable BR2_BINFMT_FLAT_SEP_DATA for coldfire

m68k: disable BR2_BINFMT_FLAT_SEP_DATA for coldfire

BR2_BINFMT_FLAT_SEP_DATA can be used to create XIP userland and works fine
for m68k. Unfortunately a lot of basic packages as pcre are not compileable
because of a CPU or hardware limitation. The reason for failing are very
big functions used in the libraries or application code.

Typical errors are:

Fatal error: Tried to convert PC relative branch to absolute jump
or
error: value -yyyyy out of range

Add kernel patch from 4ec5542679264bc06a0356ef92f06ad7a0abe06d to make
BR2_BINFMT_FLAT_ONE compiled firmware work fine.

Fixes:
  http://autobuild.buildroot.net/results/20b/20b1586757450d6aad8583ad7a787a7ca11acef1/
  http://autobuild.buildroot.net/results/d31/d311955ada1ffcd7f69e82965c8fe33eabe488cd/

Signed-off-by: Waldemar Brodkorb <wbx@openadk.org>
[Thomas: add comment in Config.in file about sep-data existing on m68k,
but being disabled due to build issues with numerous packages.]
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>