68000 CPUs do not save format in the exception stack frame.
This patch adds feature checking to prevent format saving for 68000.
m68k_ret() already includes this modification, this patch fixes
the exception processing function too.

Signed-off-by: Pavel Dovgalyuk <Pavel.Dovgaluk@ispras.ru>
Reviewed-by: Laurent Vivier <laurent@vivier.eu>
Message-Id: <20180413133041.29509.59064.stgit@pasha-VirtualBox>
Signed-off-by: Laurent Vivier <laurent@vivier.eu>