hw/nvram: Introduce Xilinx Versal eFuse device

hw/nvram: Introduce Xilinx Versal eFuse device

This implements the Xilinx Versal eFuse, an one-time
field-programmable non-volatile storage device.  There is
only one such device in the Xilinx Versal product family.

This device has two separate mmio interfaces, a controller
and a flatten readback.

The controller provides interfaces for field-programming,
configuration, control, and status.

The flatten readback is a cache to provide a byte-accessible
read-only interface to efficiently read efuse array.

Co-authored-by: Edgar E. Iglesias <edgar.iglesias@xilinx.com>
Co-authored-by: Sai Pavan Boddu <sai.pavan.boddu@xilinx.com>
Signed-off-by: Edgar E. Iglesias <edgar.iglesias@xilinx.com>
Signed-off-by: Sai Pavan Boddu <sai.pavan.boddu@xilinx.com>
Signed-off-by: Tong Ho <tong.ho@xilinx.com>
Message-id: 20210917052400.1249094-3-tong.ho@xilinx.com
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>