Hexagon (target/hexagon) Use QEMU decodetree (16-bit instructions)

Hexagon (target/hexagon) Use QEMU decodetree (16-bit instructions)

Section 10.3 of the Hexagon V73 Programmer's Reference Manual

A duplex is encoded as a 32-bit instruction with bits [15:14] set to 00.
The sub-instructions that comprise a duplex are encoded as 13-bit fields
in the duplex.

Create a decoder for each subinstruction class (a, l1, l2, s1, s2).

Extend gen_trans_funcs.py to handle all instructions rather than
filter by instruction class.

There is a g_assert_not_reached() in decode_insns() in decode.c to
verify we never try to use the old decoder on 16-bit instructions.

Signed-off-by: Taylor Simpson <ltaylorsimpson@gmail.com>
Reviewed-by: Brian Cain <bcain@quicinc.com>
Message-Id: <20240115221443.365287-3-ltaylorsimpson@gmail.com>
Signed-off-by: Brian Cain <bcain@quicinc.com>