ata: ahci_xgene: Add AHCI Support for 2nd HW version of APM X-Gene SoC AHCI SATA Host controller.

This patch enables full AHCI feature support for APM X-Gene SoC SATA
host controller. The following errata's are removed:

1. 2a0bdff6 ("ahci-xgene: fix the dma state machine lockup for the
                 IDENTIFY DEVICE PIO mode command")
2. 09c32aaa ("ahci_xgene: Fix the dma state machine lockup for the
                 ATA_CMD_SMART PIO mode command")
3. 1540035d ("ahci_xgene: Implement the xgene_ahci_poll_reg_val to
                 support PMP")
4. a3a84bc7 ("ahci_xgene: Implement the workaround to support PMP
                 enumeration and discovery")
5. 1102407b ("ahci_xgene: Fix the DMA state machine lockup for the
                 ATA_CMD_PACKET PIO mode command")
6. 72f79f9e ("ahci_xgene: Removing NCQ support from the APM X-Gene
		SoC AHCI SATA Host Controller driver")

In addition, enable PMP support for APM X-Gene SoC and enable FBS
support for second generation APM X-Gene SoC.

Signed-off-by: Suman Tripathi <stripathi@apm.com>
Signed-off-by: Tejun Heo <tj@kernel.org>