arm64: dts: Add S2MPS15 PMIC node on exynos7-espresso

This patch adds PMIC (S2MPS15) node on Espresso board,
which includes regulators and pmic-clk sub-nodes.

This patch also adds {vmmc,vqmmc}-supply properties for mmc2 node.

Signed-off-by: Abhilash Kesavan <a.kesavan@samsung.com>
Signed-off-by: Alim Akhtar <alim.akhtar@samsung.com>
Reviewed-by: Javier Martinez Canillas <javier@osg.samsung.com>
Reviewed-by: Krzysztof Kozlowski <k.kozlowski@samsung.com>
Signed-off-by: Krzysztof Kozlowski <k.kozlowski@samsung.com>