selftests: sparc64: memory: Add tests for privileged ADI driver

selftests: sparc64: memory: Add tests for privileged ADI driver

This patch contains a few basic tests for verifying proper
functionality of the sparc64 privileged ADI driver.

The tests also report simple statistics of how long the read(),
write(), and seek() operations took to complete.

	Syscall Call    AvgTime AvgSize
	        Count   (ticks) (bytes)
	-------------------------------
	read          3  167134    8133
	pread         4  137217    6741
	write         3   73787    8133
	pwrite        4   65832    6741
	seek         10    2422       0

	Ran 8 tests
	All tests passed

Orabug: 26170808
Reviewed-by: Allen Pais <allen.pais@oracle.com>
Signed-off-by: Tom Hromatka <tom.hromatka@oracle.com>
Signed-off-by: Allen Pais <allen.pais@oracle.com>