arm64: zynqmp: SoC changes for v4.20 - Adding firmware API for SoC with debugfs interface Firmware driver communicates to Platform Management Unit (PMU) by using SMC instructions routed to Arm Trusted Firmware (ATF). Initial version adds support for base firmware driver with query and clock APIs. EEMI spec is available here: https://www.xilinx.com/support/documentation/user_guides/ug1200-eemi-api.pdf