commit 75646e75 upstream.

Some machines (eg. Lenovo Z480) ECs are not stable during boot up
and causes battery driver fails to be loaded due to failure of getting
battery information from EC sometimes. After several retries, the
operation will work. This patch is to retry to get battery information 5
times if the first try fails.

Link: https://bugzilla.kernel.org/show_bug.cgi?id=75581Reported-and-tested-by: naszar <naszar@ya.ru>
Signed-off-by: Lan Tianyu <tianyu.lan@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
[bwh: Backported to 3.2: acpi_battery_update() doesn't take a second parameter]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>