Build packages for generic Arm architecture

Build packages for generic Arm architecture

The current aarch64 version of VPP package distro in cloud repository
 (https://packagecloud.io/fdio/master/ubuntu), is built on a ThunderX server,
using some arch-specific options, for example, 128Byte cache line size,
 T=arm64-thunderx-linuxapp-gcc, RTE_MACHINE=thunderx

The patch is trying to build package distro with aarch64 generic features,
for both binary type targets, e.g., build/build-release, and package type
targets, e.g., pkg-deb/pkg-rpm, with the generic options, e.g.,
128Byte cache line size, T=arm64-armv8a-linuxapp-gcc, RTE_MACHINE=armv8a

If end users want to build arch specific optimized image,
TARGET_PLATFORM variable could be used, as below example,

$ make build-release/pkg-deb TARGET_PLATFORM=thunderx

Change-Id: If78bca8709fe83db6a95e8c26346f206bf5ea71d
Signed-off-by: Lijian Zhang <Lijian.Zhang@arm.com>
Reviewed-by: Sirshak Das <Sirshak.Das@arm.com>
Reviewed-by: Honnappa Nagarahalli <Honnappa.Nagarahalli@arm.com>