gpu mem bpf program - switch to LICENSE macro

Without this resulting .o is incorrectly formatted
and fails to load with newer bpfloader.

Bug: 190519702
Test: atest, TreeHugger - existing bpf programs load
  examination of bpfloader logs
Signed-off-by: Maciej Żenczykowski <maze@google.com>
Change-Id: Ie1a3ed0cdaebc533e4533ed5bfefd369ec2a87b3