The previous commit to this file meant thumb was always being turned on
even when TUNE_FEATURES did not contain "thumb". This is clearly wrong
and this patch corrects this so thumb options are no longer specified
in that case.
(From OE-Core rev: 4b5e8074f8aca59b09421db464ce652e84f898f2)
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>