Add the Soc- / machine-dependent parts of imx6 support.
The PAL_PTCE_INFO function returns the counts and strides of the
outer and inner loop as 32-bit integers mux'd in 64-bit return
values. Change our data types for the count and stride to match
and simplify/adjust accordingly.
Note that with this change the defaults of the ptc.e parameters
have changed. Since all hardware is supposed to support the PAL
call, there should be no impact. Even ski is unaffected, because
the TC is re-initialized without considering the virtual address.
So, as long as we call ptc.e at least once, we're good. That's
what the new defaults do.
Most processor implementations need but a single ptc.e to purge
the entire TC anyway...
Install include files for netpfil/pf when requested by the Makefile

Reviewed by:	glebius
Add dts source for imx6 SoCs and for Wandboard boards.

The imx6.dtsi is incomplete, but has enough to support devices that work
right now.  Eventually it will need to be split into several files that
account for the differences between SoCs in the imx6 family.

The board config for Wandboard Dual is untested.  Solo and Quad work, but
one one core is turned on for the quad right now (baby steps).