mfd: rk808: Fix RK818 ID template

The Rockchip PMIC driver can automatically detect connected component
versions by reading the ID_MSB and ID_LSB registers. The probe function
will always fail with RK818 PMICs because the ID_MSK is 0xFFF0 and the
RK818 template ID is 0x8181.

This patch changes this value to 0x8180.

Fixes: 9d6105e1 ("mfd: rk808: Fix up the chip id get failed")
Cc: stable@vger.kernel.org
Cc: Elaine Zhang <zhangqing@rock-chips.com>
Cc: Joseph Chen <chenjh@rock-chips.com>
Signed-off-by: Daniel Schultz <d.schultz@phytec.de>
Signed-off-by: Heiko Stuebner <heiko@sntech.de>
Signed-off-by: Lee Jones <lee.jones@linaro.org>