ARM: dts: rockchip: correct the name of REG8 for rk3288-evb-act8846

According to the schematic, the name of REG8 should be vcc_tp, rather
than vcca_tp.

Signed-off-by: Chris Zhong <zyw@rock-chips.com>
Signed-off-by: Heiko Stuebner <heiko@sntech.de>