Remove dep file option from generate_binaries.py

The binaries generated from the script will be regenerated upon each
compilation, so there should be no need to have a dependency file
specifying the output files from said script.

Signed-off-by: Jonny Svärd <jonny.svaerd@arm.com>
Change-Id: Ic9be950c119f6263725590b34d44d075ff65b370