cbfstool: actually use no-ms-bitfields flag on mingw

It was added to an unused variable.

Change-Id: I869ffdda7e04b5c615931473c760d66b803fb98b
Signed-off-by: Patrick Georgi <pgeorgi@chromium.org>
Reviewed-on: http://review.coreboot.org/11673
Tested-by: build bot (Jenkins)
Reviewed-by: Aaron Durbin <adurbin@chromium.org>
1 file changed