Add support for the USB PHY on imx6 SoCs.  Pretty minimal at this point,
but enough to get usb host mode working.


git-svn-id: svn+ssh://svn.freebsd.org/base/head@257452 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f
Add stubbed-out imx6 support for clocks and power management.  This
contains little more than a few stub functions required to keep the
linker happy, but it's enough to let early imx6 development proceed.


git-svn-id: svn+ssh://svn.freebsd.org/base/head@257453 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f
Add sdhci driver glue for imx family SoCs.  This should support both uSDHC
(newer SoCs) and eSDHC (older SoCs), but the eSDHC support is untested and
likely to need some tweaking.


git-svn-id: svn+ssh://svn.freebsd.org/base/head@257454 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f