remove BpfLevel and getBpfSupportLevel in favour of isAtLeastKernelVersion am: dcb5228f2c

Original change: https://android-review.googlesource.com/c/platform/system/bpf/+/1552952

MUST ONLY BE SUBMITTED BY AUTOMERGER

Change-Id: I3767f0f75b766b1251ab070ec6d188b1d2efc243