perf symbols: kallsyms__delta() needs the kmap, not the map

perf symbols: kallsyms__delta() needs the kmap, not the map

It was only using the map to obtain its kmap, so do the validation in
its called, __dso__load_kallsyms() and pass the kmap, that will be used
in the following patches in similar simplifications.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: https://lkml.kernel.org/n/tip-u6p9hbonlqzpl6o1z9xzxd75@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>