u-boot-omnia: change PKG_VERSION to force jenkins not to build from cached sources

It would appear that the build system has the git sources downloaded and tarballed so that it doesn't have to download every time the package is being built. But PKG_RELEASE is not part of the file name, and so the build system does not recognize the sources have changed and have to be downloaded again (even though PKG_SOURCE_VERSION has changed).

Change PKG_VERSION (and drop PKG_RELEASE to 1) to force build system to build from newer sources.