bpf: Allow overriding kernel version

This allows devices pretend they are on a different kernel version in
order to support different bpf features in case kernel backports are in
place.

Test: set ro.bpf.kver_override=5.4.186 in product.prop on sm8150 device
      based on 4.14 kernel with 5.4 bpf backported, boot
Change-Id: I50357ee832b01b11e499278244f77244c904e3e9
1 file changed