x86/tsx: Minor cleanup and improvements

x86/tsx: Minor cleanup and improvements

 * Introduce cpu_has_arch_caps and replace boot_cpu_has(X86_FEATURE_ARCH_CAPS)
 * Read CPUID data into the appropriate boot_cpu_data.x86_capability[]
   element, as subsequent changes are going to need more cpu_has_* logic.
 * Use the hi/lo MSR helpers, which substantially improves code generation.

No practical change.

Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Acked-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Roger Pau Monné <roger.pau@citrix.com>