- Copy stable/10@296371 to releng/10.3 in preparation for 10.3-RC1
builds.
- Update newvers.sh to reflect RC1.
- Update __FreeBSD_version to reflect 10.3.
- Update default pkg(8) configuration to use the quarterly branch.

Approved by: re (implicit)

MFC r282516:

Add the code necessary to run the imx6 chip at its lowest clock/power
operating point (396MHz/950mV).

MFC r268838, r277644:

Add support for Toradex Apalis i.MX6 development board.

Add support for imx6 audio transmitting, include drivers for:
o Digital Audio Multiplexer (AUDMUX)
o Smart Direct Memory Access Controller (SDMA)
o Synchronous Serial Interface (SSI)

MFC r271055, r271084, r271094:

Add a function to get the frequency of the AHB bus. Another stopgap
function until we have full clock support for imx6.

The imx5x and imx6 chips have an onboard IOMUX device which also contains a
few "general purpose registers" whose values control chip behavior in ways
that have nothing to do with IO pin mux control. Define a simple API that
other soc-specific code can use to read and write the registers, and provide
the imx51 implementation of them.

Fix a typo.

MFC 264977:

Stop calling imx51_ccm_foo() clock functions from imx6 code. Instead
define a few imx_ccm_foo() functions that are implemented by the imx51
or imx6 ccm code.

Stop calling imx51_ccm_foo() clock functions from imx6 code. Instead
define a few imx_ccm_foo() functions that are implemented by the imx51 or
imx6 ccm code. Of course, the imx6 ccm code is still more a wish than
reality, so for now its implementations just return hard-coded numbers.