configs/rdv2: Add ArmVirtKvmTool to rdv2 UEFI package list

Define and add ArmVirtKvmTool package to the existing list of RD-V2
UEFI packages to build and provide firmware that can be used for UEFI
based guest OS boot in a virtualized environment created with the help
of kvmtool and linux KVM.

Also define EDK2_OUT_DIR flag to point to the output directory to
build ArmVirtKvmTool as current build-scripts don't create any
ArmVirtKvmTool-$(ARCH) output directory.

Signed-off-by: Sathyam Panda <sathyam.panda@arm.com>
Change-Id: Idd204fe402f98c81f399bcd0bc79752050a0a624