tcg-aarch64: Introduce tcg_out_insn_3312, _3310, _3313

tcg-aarch64: Introduce tcg_out_insn_3312, _3310, _3313

Replace aarch64_ldst_op_data with AArch64LdstType, as it wasn't encoded
for the proper shift for the field and was confusing.

Merge aarch64_ldst_op_data, AArch64LdstType, and a few stray opcode bits
into a single I3312_* argument, eliminating some magic numbers from the
helper functions.

Reviewed-by: Claudio Fontana <claudio.fontana@huawei.com>
Signed-off-by: Richard Henderson <rth@twiddle.net>