ACPI: /proc/acpi/alarm parsing: handle large numbers properly

ACPI: /proc/acpi/alarm parsing: handle large numbers properly

In function acpi_system_write_alarm in file drivers/acpi/sleep/proc.c,
big sec, min, hr, mo, day and yr are counted twice to get reasonable
values, that is very superfluous, we can do that only once.

In additon, /proc/acpi/alarm can set a related value which can be
specified as YYYY years MM months DD days HH hours MM minutes SS
senconds, it isn't a date, so you can specify as +0000-00-00 96:00:00
, that means 3 days later, current code can't handle such a case.

This patch removes unnecessary code and does with the aforementioned
situation.

Before applying this patch:

[root@localhost /]# cat /proc/acpi/alarm
2007-12-00 00:00:00
[root@localhost /]# echo "0000-00-00 96:180:180" > /proc/acpi/alarm
[root@localhost /]# cat /proc/acpi/alarm
0007-12-02 **:**:**
[root@localhost /]#

After applying this patch:

[root@localhost ~]# echo "2007-12-00 00:00:00" > /proc/acpi/alarm
[root@localhost ~]# cat /proc/acpi/alarm
2007-12-00 00:00:00
[root@localhost ~]# echo "0000-00-00 96:180:180" > /proc/acpi/alarm
[root@localhost ~]# cat /proc/acpi/alarm
0007-12-04 03:03:00
[root@localhost ~]#

Signed-off-by: Yi Yang <yi.y.yang@intel.com>
Signed-off-by: Len Brown <len.brown@intel.com>