target/xtensa: don't require opcode table sorting

Requirement for alphabetical opcode sorting in opcode tables is awkward
and does not allow sharing implementation between multiple opcodes.
Use hash tables to find opcodes by name. Move implementation from the
translate.c to the helper.c to its only user and remove declaration from
the cpu.h

Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
3 files changed