mvebu: pinctrl: apply SDHCI PHY config for A7K

Current pin control driver applies SDHCI PHY MUX selection
when board DT calls for eMMC function on MPP wires.
However, for CP side eMMC, only the "armada-8k-cpm-pinctrl"
compatibility string is taken into account, which causes
CP-SDHCI on Armada-7K boards to fail.
This patch adds "armada-7k-pinctrl" compatibility string
handling for the CP-SDHCI PHY configuration case.

Signed-off-by: Konstantin Porotchkin <kostap@marvell.com>
Reviewed-by: Igal Liberman <igall@marvell.com>
Reviewed-by: Stefan Roese <sr@denx.de>