- 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 r266937:

Export two new settings for the AM335x PWM, the clock prescaler (clkdiv)
and the actual PWM frequency.

Enforce the maximum value for the period sysctl.

The frequency systcl now allows the direct setting of the PWM frequency
(it will try to find the better clkdiv and period for a given frequency,
i.e. the ones that will give the better PWM resolution).

This allows the use lower frequencies on the PWM. Without changing the
clock prescaler the minimum PWM frequency was 1.52kHz.

PWM frequencies checked with an osciloscope.

PWM output tested with some R/C servos at 50Hz.

MFC r261410

Follow r261352 by updating all drivers which are children of simplebus
to check the status property in their probe routines.

Copy head (r256279) to stable/10 as part of the 10.0-RELEASE cycle.

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

Add support for ePWM submodule of PWMSS

ePWM is controlled by sysctl nodes dev.am335x_pwm.N.period,
dev.am335x_pwm.N.dutyA and dev.am335x_pwm.N.dutyB that controls
PWM period and duty cycles for channels A and B respectively.

Period and duty cycle are measured in clock ticks. Default
clock frequency for AM335x PWM subsystem is 100MHz

Add PWM module driver for AM335x. Only eCAS subsystem is supported

Export function to configure eCAS submodule from another drivers.
It's used to control LCD panel backlight on AM335x EVM.