x86/alternative: Use ALTERNATIVE_TERNARY() in _static_cpu_has()

_static_cpu_has() contains a completely open coded version of
ALTERNATIVE_TERNARY(). Replace that with the macro instead.

Signed-off-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20210311142319.4723-8-jgross@suse.com