tools/power/x86/intel-speed-select: Fix CPU count display

Fix CPU count display for power domain != 0. In the function
punit_id is always 0, so it never incremented cpu count for power
domain id != 0.

Update punit_id after call to update_punit_cpu_info() to what is
actually received from the kernel.

Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>