soc/intel/common: round PM Timer emulation frequency multiplier

Round the PM Timer emulation frequency multiplier to the closest value
to increase precision.

Test: compared hexdumps of CML binaries for the expected result:
      before: 0x262E8B51, after: 0x262E8B52

Change-Id: Iafd645c248fc17943ea4be558ed7d01a301ba809
Signed-off-by: Michael Niewöhner <foss@mniewoehner.de>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/57943
Reviewed-by: Nico Huber <nico.h@gmx.de>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

src/soc/intel/common/block/cpu/pm_timer_emulation.c

@@ -1,5 +1,6 @@
 /* SPDX-License-Identifier: GPL-2.0-only */
 
+#include <commonlib/helpers.h>
 #include <cpu/x86/msr.h>
 #include <intelblocks/cpulib.h>
 #include <intelblocks/msr.h>
@@ -18,7 +19,7 @@ void enable_pm_timer_emulation(void)
 	 * (clock * msr[63:32]) >> 32 = target frequency.
 	 * Back solve the multiplier so the 3.579545MHz ACPI timer frequency is used.
 	 */
-	msr.hi = (3579545ULL << 32) / CONFIG_CPU_XTAL_HZ;
+	msr.hi = DIV_ROUND_CLOSEST((3579545ULL << 32), CONFIG_CPU_XTAL_HZ);
 	/* Set PM1 timer IO port and enable */
 	msr.lo = (EMULATE_DELAY_VALUE << EMULATE_DELAY_OFFSET_VALUE) |
 		  EMULATE_PM_TMR_EN | (ACPI_BASE_ADDRESS + PM1_TMR);