linux-overo : Update usrp_e driver with latest bus timing.

Signed-off-by: Philip Balister <philip@balister.org>
linux-overo : Generate uImage.

Signed-off-by: Philip Balister <philip@balister.org>
usrp-base-image : Add swig to the nativesdk list.

Signed-off-by: Philip Balister <philip@balister.org>
usrp-base-image : Add python-shell to sdk.

Also broke sdk addition var into mulitple lines.

Signed-off-by: Philip Balister <philip@balister.org>