x86/apic: Convert the TSC deadline timer matching to steppings macro

... and get rid of the function pointers which would spit out the
microcode revision based on the CPU stepping.

Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Mark Gross <mgross.linux.intel.com>
Cc: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20200506071516.25445-4-bp@alien8.de