bpf: mark/remove unused arguments and remove an unused function

This patch does a little bit of cleanup by removing some unused
arguments, or marking them as unused.  It also removes the function
ctfc_debuginfo_early_finish_p and the corresponding hook macro
definition, which are not used by GCC.

gcc/
	* config/bpf/bpf.c (bpf_handle_preserve_access_index_attribute):
	Mark arguments `args' and flags' as unused.
	(bpf_core_newdecl): Remove unused local `newdecl'.
	(bpf_core_newdecl): Remove unused argument `loc'.
	(ctfc_debuginfo_early_finish_p): Remove unused function.
	(TARGET_CTFC_DEBUGINFO_EARLY_FINISH_P): Remove definition.
	(bpf_core_walk): Do not pass a location to bpf_core_newdecl.