arm64: selftests: Generate all the possible logical immediates as a header

Aarch64 has instructions to generate reasonably complicated 32 or 64
bit masks from only 13 bits of information. To test the in-kernel code
that spots the pattern to produce the instruction encoding a golden set
of values is needed.

A header file containing these is large. Instead, generate every possible
instruction encoding, and its decoded immediate, based on the arm-arm's
DecodeBitMasks() pseudocode. These are output in a format that can be used
in a header file for the test.

Having the golden values in a header file allows them to be inspected,
and checked against a trusted source. The generation program can be told
to pass each value through objdump and compared.

Unsat's jitterbug project has a python script that does this too, but
the license isn't clear from the github repository.

Link: https://lore.kernel.org/linux-arm-kernel/CAB-e3NRCJ_4+vkFPkMN67DwBBtO=sJw

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CC: Luke Nelson <luke.r.nels@gmail.com>
Signed-off-by: James Morse <james.morse@arm.com>