rtc: cmos: Refactor code by using the new dmi_get_bios_year() helper

Refactor code by using the new dmi_get_bios_year() helper instead of
open coding its functionality. This also makes logic slightly clearer.

No changes intended.

Cc: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Tested-by: Guilherme G. Piccoli <gpiccoli@canonical.com>
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Link: https://lore.kernel.org/r/20200123131437.28157-3-andriy.shevchenko@linux.intel.com
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

drivers/rtc/rtc-cmos.c

@@ -1197,8 +1197,6 @@ static void rtc_wake_off(struct device *dev)
 /* Enable use_acpi_alarm mode for Intel platforms no earlier than 2015 */
 static void use_acpi_alarm_quirks(void)
 {
-	int year;
-
 	if (boot_cpu_data.x86_vendor != X86_VENDOR_INTEL)
 		return;
 
@@ -1208,8 +1206,10 @@ static void use_acpi_alarm_quirks(void)
 	if (!is_hpet_enabled())
 		return;
 
-	if (dmi_get_date(DMI_BIOS_DATE, &year, NULL, NULL) && year >= 2015)
-		use_acpi_alarm = true;
+	if (dmi_get_bios_year() < 2015)
+		return;
+
+	use_acpi_alarm = true;
 }
 #else
 static inline void use_acpi_alarm_quirks(void) { }