bpftool: Remove inclusion of utilities.mak from Makefiles

Bpftool's Makefile, and the Makefile for its documentation, both include
scripts/utilities.mak, but they use none of the items defined in this
file. Remove the includes.

Fixes: 71bb428f ("tools: bpf: add bpftool")
Signed-off-by: Quentin Monnet <quentin@isovalent.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20211110114632.24537-3-quentin@isovalent.com

tools/bpf/bpftool/Documentation/Makefile

 # SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
 include ../../../scripts/Makefile.include
-include ../../../scripts/utilities.mak
 
 INSTALL ?= install
 RM ?= rm -f

tools/bpf/bpftool/Makefile

 # SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
 include ../../scripts/Makefile.include
-include ../../scripts/utilities.mak
 
 ifeq ($(srctree),)
 srctree := $(patsubst %/,%,$(dir $(CURDIR)))