soc/intel/skylake: Add config for cpu base clock frequency

Add config for cpu base clock frequency(Mhz) and replace current
refrence from soc/cpu.h with config option.

Change-Id: Idf8e85f7ae6d965fa987a4f5c4905503ee354d69
Signed-off-by: Aamir Bohra <aamir.bohra@intel.com>
Reviewed-on: https://review.coreboot.org/20016
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Aaron Durbin <adurbin@chromium.org>

src/soc/intel/skylake/cpu.c

@@ -320,7 +320,7 @@ static void set_max_ratio(void)
 	wrmsr(IA32_PERF_CTL, perf_ctl);
 
 	printk(BIOS_DEBUG, "cpu: frequency set to %d\n",
-	       ((perf_ctl.lo >> 8) & 0xff) * CPU_BCLK);
+	       ((perf_ctl.lo >> 8) & 0xff) * CONFIG_CPU_BCLK_MHZ);
 }
 
 static void set_energy_perf_bias(u8 policy)