tcg-arm: Handle constant arguments to add2/sub2 We get to re-use the _rIN and _rIK subroutines to handle the various combinations of add vs sub. Fold the << 21 into the opcode enum values so that we can explicitly add TO_CPSR as desired. Reviewed-by: Aurelien Jarno <aurelien@aurel32.net> Signed-off-by: Richard Henderson <rth@twiddle.net>