char: sparc64: Add privileged ADI driver

SPARC M7 and newer processors utilize ADI to version and
protect memory. This driver is capable of reading/writing
ADI/MCD versions from privileged user space processes.
Addresses in the adi file are mapped linearly to physical
memory at a ratio of 1:adi_blksz. Thus, a read (or write)
of offset K in the file operates upon the ADI version at
physical address K * adi_blksz. The version information
is encoded as one version per byte. Intended consumers
are makedumpfile and crash.

Signed-off-by: Tom Hromatka <tom.hromatka@oracle.com>
Reviewed-by: Khalid Aziz <khalid.aziz@oracle.com>
Reviewed-by: Shannon Nelson <shannon.nelson@oracle.com>
Reviewed-by: Anthony Yznaga <anthony.yznaga@oracle.com>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: David S. Miller <davem@davemloft.net>