linux-imx

ata: imx: enhance the codes to enable imx8qm sata

- Add one ext_osc parameter for imx8qm ahci.
  Add one parameter to distinguish the different ref_clk
  source, internal pll or the external osc.
  NOTE: The value of the ext_osc should be aligned to the one
  of the PCIe's, since both of them share one ref_clk source.
- Fix can't find ahb clk issue.
  The ahb clock is not mandatory required by iMX8QM SATA, fetch it only
  when there is "ahb" clock.
- Specify the 32-bit dma limitation and the softreset for iMX8QM SATA.
- Use the standard ahci_error_handler on iMX8QM SATA.

Signed-off-by: Richard Zhu <hongxing.zhu@nxp.com>