scripts/kallsyms: rename build_initial_tok_table()

Except for the function build_initial_tok_table(), no token abbreviation
is used elsewhere.

$ cat scripts/kallsyms.c | grep tok | wc -l
33
$ cat scripts/kallsyms.c | grep token | wc -l
31

Here, it would be clearer to use the full name.

Signed-off-by: Zhen Lei <thunder.leizhen@huawei.com>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>