arm64: Add APM X-Gene SoC 15Gbps Multi-purpose PHY DTS entries

This patch adds the DTS entries for the APM X-Gene SoC 15Gbps Multi-purpose
PHY driver. The PHY for SATA controller 2 and 3 are enabled by default.

Signed-off-by: Loc Ho <lho@apm.com>
Signed-off-by: Tuan Phan <tphan@apm.com>
Signed-off-by: Suman Tripathi <stripathi@apm.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Tejun Heo <tj@kernel.org>