Add aarch64 as a valid machine to cpuburn recipe and split compilation
task.
The only source file which supports the aarch64 build is cpuburn-a53.S,
and in case if TUNE is set to aarch64 - this should be the only file to
be assembled to the application.
In case of 32-bit build - all sources are compiled as they are, since
cpuburn-a53.S supports both 32- and 64-bit tunes.
Signed-off-by: Andrey Zhizhikin <andrey.z@gmail.com>
Signed-off-by: Khem Raj <raj.khem@gmail.com>