power: rk8xx: fix display name for RK808

Commit 2ce40542 ("power: rk8xx: properly print all supported PMICs
name") fixed all PMICs name that were broken but broke the only one that
was not broken already: RK808. This one is a special case because the ID
registers are marked as reserved and always return 0, so the variant
cannot be derived the same way it is done for other PMICs from Rockchip.

Fixes: 2ce40542 ("power: rk8xx: properly print all supported PMICs name")
Signed-off-by: Quentin Schulz <quentin.schulz@cherry.de>
Reviewed-by: Dragan Simic <dsimic@manjaro.org>