ACPI: battery: fix some coding style issues

Fix some coding style issues reported by checkpatch.pl, including the
following types:

WARNING: Block comments use * on subsequent lines
WARNING: Block comments use a trailing */ on a separate line
ERROR: code indent should use tabs where possible
WARNING: Missing a blank line after declarations
ERROR: spaces required around that '?' (ctx:WxV)
WARNING: Block comments should align the * on each line

Signed-off-by: Xiaofei Tan <tanxiaofei@huawei.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>