target/m68k: don't word align SP in stack frame if M68K_FEATURE_UNALIGNED_DATA feature enabled

Commit a9431a03 ("target/m68k: add M68K_FEATURE_UNALIGNED_DATA feature") added
a new feature for processors from the 68020 onwards which do not require data
accesses to be word aligned.

Unfortunately the original commit missed an additional case whereby the SP is
still word aligned when setting up an additional format 1 stack frame so add the
necessary M68K_FEATURE_UNALIGNED_DATA feature guard.

Signed-off-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
Fixes: a9431a03 ("target/m68k: add M68K_FEATURE_UNALIGNED_DATA feature")
Reviewed-by: Laurent Vivier <laurent@vivier.eu>
Message-Id: <20220108180453.18680-1-mark.cave-ayland@ilande.co.uk>
Signed-off-by: Laurent Vivier <laurent@vivier.eu>