First, the SATA_MV driver can only build on kirkwood or mvebu platforms
due to header requirements, so add that as a dependency here. Second,
SYS_SATA_MAX_DEVICE is also used by the API code so allow it to be
configured in that case.
Reviewed-by: Tony Dinh <mibodhi@gmail.com>
Signed-off-by: Tom Rini <trini@konsulko.com>