kselftest/arm64: Improve output for skipped TPIDR2 ABI test

kselftest/arm64: Improve output for skipped TPIDR2 ABI test

When TPIDR2 is not supported the tpidr2 ABI test prints the same message
for each skipped test:

  ok 1 skipped, TPIDR2 not supported

which isn't ideal for test automation software since it tracks kselftest
results based on the string used to describe the test. This is also not
standard KTAP output, the expected format is:

  ok 1 # SKIP default_value

Updated the program to generate this, using the same set of test names that
we would run if the test actually executed.

Signed-off-by: Mark Brown <broonie@kernel.org>
Link: https://lore.kernel.org/r/20231124-kselftest-arm64-tpidr2-skip-v1-1-e05d0ccef101@kernel.org
Signed-off-by: Will Deacon <will@kernel.org>