arm64: zynqmp: Enable capsule update

Enable EFI capsule update features to be enabled by default also with all
dfu valid options for ZynqMP.

This feature was tested on Xilinx ZynqMP zcu104 board with defining
dfu_alt_info="mmc 0:1=boot.bin fat 0 1;u-boot.itb fat 0 1"
and
dfu_alt_info="sf 0:0=boot.bin raw 0 0x50000;u-boot.itb raw 0x80000
0x500000".

There is a need to increase malloc size for getting dfu mmc to work.

Signed-off-by: Michal Simek <michal.simek@xilinx.com>
CC: Sughosh Ganu <sughosh.ganu@linaro.org>
CC: Ilias Apalodimas <ilias.apalodimas@linaro.org>
CC: Heinrich Schuchardt <xypron.glpk@gmx.de>