adds xilinx virtex bga packages
adds the parameters for the virtex packages.
Important notes:
Virtex-7 FPGA Packages Notes:
- FFG1157 and FFG1158 have same footprint and same 3D package and are therefore in one footprint under FFG1157
- FFG1926, FFG1927, FFG1928 and FFG1930 have same footprint and same 3D package and are therefore in one footprint under FFG1926
- FLG1925, FLG1926, FLG1928 and FLG1930 have same footprint and same 3D package and are therefore in one footprint under FLG1925
- RF1157 and RF1158 have same footprint and same 3D package and are therefore in one footprint under RF1157
Pinging @ObKo as the package names could be a bit different than for Artix and Spartan because some footprints combine mulitple names
Edited by Joel Guittet