x86/smp: Remove unnecessary assignment to local var freq_scale

Coverity warns of an unused value in arch_scale_freq_tick():

  CID 100778 (#1 of 1): Unused value (UNUSED_VALUE)
  assigned_value: Assigning value 1024ULL to freq_scale here, but that stored
  value is overwritten before it can be used.

It was introduced by commit:

  e2b0d619 ("x86, sched: check for counters overflow in frequency invariant accounting")

Remove the variable initializer.

Signed-off-by: Tim Gardner <tim.gardner@canonical.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Giovanni Gherdovich <ggherdovich@suse.cz>
Link: https://lkml.kernel.org/r/20210910184405.24422-1-tim.gardner@canonical.com