decodetree: Add support for 64-bit instructions

decodetree: Add support for 64-bit instructions

Allow '64' to be specified for the instruction width command line params
and use the appropriate extract and deposit functions in that case.

This will be used to implement the new 64-bit Power ISA 3.1 instructions.

Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Signed-off-by: Luis Pires <luis.pires@eldorado.org.br>
Message-Id: <CP2PR80MB3668E123E2EFDB0ACD3A46F1DA759@CP2PR80MB3668.lamprd80.prod.outlook.com>
[rth: Drop the change to the field type; use bitop_width instead of separate
variables for extract/deposit; use "ull" for 64-bit constants.]
Reviewed-by: Luis Pires <luis.pires@eldorado.org.br>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>