xilinx: zynqmp: Add support for runtime dfu_alt_info setup

xilinx: zynqmp: Add support for runtime dfu_alt_info setup

The main reason for this to be implemented is capsule update.
Two memories are supported and tested which is MMC FAT based and QSPI
based.

For creating capsule these commands are used:
./tools/mkeficapsule --raw spl/boot.bin --index 1 capsule1.bin
./tools/mkeficapsule --raw u-boot.itb --index 2 capsule2.bin

Then transfer to SD card where these commands run:
load mmc 0 10000000 capsule1.bin
efidebug capsule update -v 10000000
load mmc 0 10000000 capsule2.bin
efidebug capsule update -v 10000000

Depends on the boot device used are binaries loaded to qspi or mmc fat
partition.
Also multiboot register is handled to make sure that the same location(id)
is used as image which is upgraded.

Two locations are used by purpose for SPL flow. If only boot.bin is used
create only one capsule.

Signed-off-by: Michal Simek <michal.simek@xilinx.com>