mmc: xenon: add AP807 compatible string

mmc: xenon: add AP807 compatible string

This patch adds new compatible string to differentiate
between the controllers versions included in the AP807
north bridge. Thanks to this change, the SoCs which use
AP807 will not run unintentionally in the 'slow mode'
with disabled UHS modes.

Signed-off-by: Marcin Wojtas <mw@semihalf.com>
Signed-off-by: Konstantin Porotchkin <kostap@marvell.com>
Link: https://lore.kernel.org/r/20210112094655.12274-3-kostap@marvell.com
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>