uboot-imx

dm: ahci: Create a local version of two SCSI functions

With driver model we need to define implementations of exec() and
bus_reset() separately for each SCSI driver. As a first step, create a
local version of each function in the AHCI driver and call each from its
global version.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>