ahci: DMA addressing fixes

ahci: DMA addressing fixes

Ensure that we are using correct physical/virtual address for
DMA buffer write and hardware register settings.

The convention is: in ahci_ioports all pointers are virtual,
that will be converted to physical address when writing to
hardware registers or into sg/cmd_tbl.

Also fixed 64bit physical address support for dwc_ahsata, ensure
higher bits are written into registers/sg properly.

Use memalign for allocating aligned buffer in dwc_ahsata so we
don't have to do our own alignment in driver.

Signed-off-by: Jiaxun Yang <jiaxun.yang@flygoat.com>