tools include: Drop ARRAY_SIZE() definition from linux/hashtable.h

tools include: Drop ARRAY_SIZE() definition from linux/hashtable.h

As tools/include/linux/kernel.h has it now, with the goodies present in
the kernel.h counterpart, i.e. checking that the parameter is an array
at build time.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/n/tip-v0b41ivu6z6dyugbq9ffa9ez@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>