ACPI / proc: Remove alarm proc file

Alarm proc file provides the info and control of RTC-CMOS alarm and
RTC CMOS driver provides wakealarm sysfs attribute for the same
purpose. The alarm file isn't compiled into kernel when RTC CMOS
driver is selected. The driver is default to be selected for x86
platform. So alarm file is default not to include. This patch is
to remove it to prepare remove /proc/acpi directory.

Signed-off-by: Lan Tianyu <tianyu.lan@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>