target-mips: Copy restrictions from ext/ins to dext/dins

The checks in dins is required to avoid triggering an assertion
in tcg_gen_deposit_tl.  The check in dext is just for completeness.
Fold the other D cases in via fallthru.

In this case the errant dins appears to be data, not code, as
translation failed to stop after a break insn.

Signed-off-by: Richard Henderson <rth@twiddle.net>
Reviewed-by: Aurelien Jarno <aurelien@aurel32.net>
Reviewed-by: Leon Alrae <leon.alrae@imgtec.com>
Signed-off-by: Leon Alrae <leon.alrae@imgtec.com>