arm64: dts: change AP807 SDHCI compatibility string

This patch adds new compatible string to AP807 DTSI to avoid
its SDHCI controller to run in "slow mode" with disabled UHS.

Signed-off-by: Marcin Wojtas <mw@semihalf.com>
Signed-off-by: Konstantin Porotchkin <kostap@marvell.com>
Signed-off-by: Gregory CLEMENT <gregory.clement@bootlin.com>