bpf: applied a bunch of checkpatch.pl fixes
While preparing the patch series to send those testing files upstream it came out that checkpatch was really not happy.
This should be only cosmetic.
Note: the hid_report_helpers.h file still complains a lot about "ERROR: Macros with complex values should be enclosed in parentheses", but give that the macro is to create fields in an array, I can't find an easy way to paper over this error.