objtool: Add __kunit_abort() to noreturns

objtool: Add __kunit_abort() to noreturns

Fixes a bunch of warnings like:

  drivers/input/tests/input_test.o: warning: objtool: input_test_init+0x1cb: stack state mismatch: cfa1=4+64 cfa2=4+56
  lib/kunit/kunit-test.o: warning: objtool: kunit_log_newline_test+0xfb: return with modified stack frame
  ...

Fixes: 260755184cbd ("kunit: Move kunit_abort() call out of kunit_do_failed_assertion()")
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20230602175453.swsn3ehyochtwkhy@treble