am335x-pru-package: new package

am335x-pru-package provides an assembler and program loader for Texas
Instrument's AM335x programmable real-time units.

[Peter: fix typo in patch description]
Signed-off-by: Frank Hunleth <fhunleth@troodon-software.com>
Signed-off-by: Yann E. MORIN <yann.morin.1998@free.fr>
Cc: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>