dt-bindings: PCI: tegra: Add PCIe slot supplies regulator

PCI-e Gen 3 x4 slot connector SFF-8643 mini SAS HD pin out defined by PCle PCI Express Base Specification Rev PCI Express Card Electro-Mechanical*

PCI-e Gen 3 x4 slot connector SFF-8643 mini SAS HD pin out defined by PCle PCI Express Base Specification Rev PCI Express Card Electro-Mechanical*

pcieslot Description Feature: PCI express 16x interface Extend M Key Slot Support

pcie 4 slot 而在伺服器的生態系統中，PCIe®更藉其高速的特性，除了原來的CEM Slot外，更演化出OCP NIC 及EDSFF E1E3等Slot來連接高速產品如運算加速卡、高速網路卡及高速儲存