samples: bpf: remove unnecessary include options in Makefile

Due to recent change of include path at commit b552d33c
("samples/bpf: fix include path in Makefile"), some of the
previous include options became unnecessary.

This commit removes duplicated include options in Makefile.
Signed-off-by: NDaniel T. Lee <danieltimlee@gmail.com>
Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net>

samples/bpf/Makefile

@@ -176,15 +176,6 @@ KBUILD_HOSTCFLAGS += -I$(srctree)/tools/lib/ -I$(srctree)/tools/include
 KBUILD_HOSTCFLAGS += -I$(srctree)/tools/perf
 
 HOSTCFLAGS_bpf_load.o += -I$(objtree)/usr/include -Wno-unused-variable
-HOSTCFLAGS_trace_helpers.o += -I$(srctree)/tools/lib/bpf/
-
-HOSTCFLAGS_trace_output_user.o += -I$(srctree)/tools/lib/bpf/
-HOSTCFLAGS_offwaketime_user.o += -I$(srctree)/tools/lib/bpf/
-HOSTCFLAGS_spintest_user.o += -I$(srctree)/tools/lib/bpf/
-HOSTCFLAGS_trace_event_user.o += -I$(srctree)/tools/lib/bpf/
-HOSTCFLAGS_sampleip_user.o += -I$(srctree)/tools/lib/bpf/
-HOSTCFLAGS_task_fd_query_user.o += -I$(srctree)/tools/lib/bpf/
-HOSTCFLAGS_xdp_sample_pkts_user.o += -I$(srctree)/tools/lib/bpf/
 
 KBUILD_HOSTLDLIBS		+= $(LIBBPF) -lelf
 HOSTLDLIBS_tracex4		+= -lrt