ARM: DT: apq8064: Add Support for ext_3p3v regulator in pci node

Ethernet needs ext_3p3v regulator to function properly. This regulator
being shared among modules, Ethernet fails when other modules which
share this regulator are not enabled.

Ethernet is connected on pcie bus and ext_3p3v regulator can be configured
through pcie. This change adds support for ext_3p3v regulator in pci DT
and make ethernet independent of others and functional.

Signed-off-by: Pramod Gurav <pramod.gurav@smartplayin.com>