iw: fix enum warnings

iw: fix enum warnings

clang warns about the misuse of enums:

reg.c:246:26: warning: implicit conversion from enumeration type 'enum command_identify_by' to different enumeration type 'enum id_input' [-Wenum-conversion]
        err = handle_cmd(state, CIB_NONE, 2, dump_args);
              ~~~~~~~~~~        ^~~~~~~~
info.c:645:26: warning: implicit conversion from enumeration type 'enum command_identify_by' to different enumeration type 'enum id_input' [-Wenum-conversion]
        err = handle_cmd(state, CIB_NONE, 2, feat_args);
              ~~~~~~~~~~        ^~~~~~~~

Signed-off-by: Brian Norris <briannorris@chromium.org>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>