Updated checksums and footprints
Added KERNEL_VERSION to config

This variable is used to designate the kernel version used.
This makes it easier to update the kernel version.
Updated submodules

* buildfiles/cross/cross-beaglebone 2bd0197...9cf39b8 (3):
  > linux: Install module.symvers, System.map, vmlinux
  > linux: Use KERNEL_VERSION variable
  > fs: Generate modules.dep

* buildfiles/cross/cross-core dd97925...5697554 (2):
  > kmod: Remove systemd service script
  > kmod: Update to version 13

* buildfiles/cross/cross-extra abe6353...0b1a29d (2):
  > libmp4v2: Fixed help2man compile issue
  > libdrm: Updated to version 2.4.45

* buildfiles/cross/cross-opt 7970a99...6ad62ff (1):
  > mc: change source URL to ftp site

* buildfiles/native/native-beaglebone 8858da2...63df4b9 (1):
  > linux: Use KERNEL_VERSION variable