MN10300: Fix register-postinc addressing misalignment handling

Fix misalignment handling of operands with register postincrement addressing.
The flag to indicate that postincrement is required should not be interpreted
as an specification of a value to be added to the address.

Also add BUGs to catch unimplemented parameter markings in the opcodes table.

Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>