mediagen arguments are not passed to pdk-mediagen script

[obbardc]

We should pass these arguments to the pdk-mediagen script, to allow run-time changes of certain parameters.

usage: pdk COMPONENT

       Generate media for a linux product.

       Options

       -h, --help
              show this help message and exit

       -a ARCH, --arch=ARCH
              Architecture

       -l LABEL, --label=LABEL
              Media label

       -o DEST, --out-file=DEST, --out-dest=DEST
              Destination for output.

[obbardc]

We should also allow an argument for the path to the repository used.