platform/x86: thinkpad_acpi: use standard charge control attribute names

The standard attributes were only introduced after the ones from
thinkpad_acpi in commit 813cab8f ("power: supply: core:
Add CHARGE_CONTROL_{START_THRESHOLD,END_THRESHOLD} properties").

The new standard attributes are aliased to their previous names,
preserving backwards compatibility.

Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>