MFC r274925: misc mdoc fixes.

MFC r271907: Add a man page for the cgem(4) driver.

MFC r266960:

Configure the analog input 7 which, on BBB, is connected to the 3V3B rail
through a voltage divisor (R163 and R164 on page 4 of BBB schematic).

Add a note about this on ti_adc(4) man page. The ti_adc(4) man page will
first appear on 10.1-RELEASE.

Suggested by: Sulev-Madis Silber (ketas)
Manual page reviewed by: brueffer (D127)

Adds the ADC driver for TI AM3xxx SoC family.

The ADC has a 12bit resolution and its raw output can be read via sysctl(8)
interface.

The driver allows the setup of ADC clock, samples average and open delay
(the number of clock cycles to wait before start the conversion).

The TSC_ADC module is set in the general purpose mode (no touchscreen
support).

Tested on Beaglebone-black.

Written based on AM335x TRM.

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

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

mdoc improvements

Polish devcfg(4) slightly: add \n after the end of every sentence.

Add Xilinx Zynq ARM/FPGA SoC support to FreeBSD/arm port.

Submitted by: Thomas Skibo <ThomasSkibo (at) sbcglobal.net>
Tested by: wkoszek (ZedBoard)
Reviewed by: wkoszek, freebsd-arm@ (no objections raised)

mdoc: drop even more redundant .Pp calls

No change in rendered output, less mandoc lint warnings.

Tool provided by: Nobuyuki Koganemaru n-kogane at syd.odn.ne.jp

Add standard MLINKs.

Provide manual page for the mge(4) device driver.

Xref altq(4).

Move npe.4 to a machine specific manpage subdirectory.