prussdrv: add prussdrv_extmem_size

Add function for querying the size of the DDR memory region that
was allocated by the driver. This lets applications check that enough
memory is available before running their PRU applications.

Signed-off-by: Frank Hunleth <fhunleth@troodon-software.com>
Fix build on FreeBSD.
add some old example
Merge pull request #4 from fhunleth/extmem_size

prussdrv: add prussdrv_extmem_size
Merge pull request #5 from rpaulo/master

Fix build on FreeBSD.
Merge pull request #6 from RoyBellingan/master

I've added some old example
Merge pull request #8 from olsonse/master

Adds python interface with interrupt fixes
simplify and correct python ctypes-based wrapper