rtc: cmos: Remove the `use_acpi_alarm' module parameter for !ACPI

Fix a problem with commit 311ee9c1 ("rtc: cmos: allow using ACPI for
RTC alarm instead of HPET") defining `use_acpi_alarm' module parameter
even for non-ACPI platforms, which ignore it.  Wrap the definition into
#ifdef CONFIG_ACPI and use a static inline wrapper function, hardcoded
to return 0 and consequently optimized away for !ACPI, following the
existing pattern with HPET handling functions.

Signed-off-by: Maciej W. Rozycki <macro@linux-mips.org>
Fixes: 311ee9c1 ("rtc: cmos: allow using ACPI for RTC alarm instead of HPET")
Cc: stable@vger.kernel.org # 4.18+
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>