Copy stable/10@r272459 to releng/10.1 as part of
the 10.1-RELEASE process.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

MFC 264981, 264983, 264985:

The freescale imx uart driver works for the whole i.MX family, so rename
the header file to not have "5xx" in the name.

Flesh out imx_uart_init() so that we're not relying on u-boot to init
the hardware (meaning uarts other than the console will work).

Reword a comment block a bit.

The freescale imx uart driver works for the whole i.MX family, so rename the
header file to not have "5xx" in the name.

Integrate Efika MX project back to home.

Sponsored by: The FreeBSD Foundation