Clears clang warnings of:

atoms.c:84:36: warning: format specifies type 'unsigned long' but
 the argument has type 'uint32_t' (aka 'unsigned int') [-Wformat]
                return makename("%s_U%lu", base, id);
                                     ~~~         ^~
                                     %u
atoms.c:86:27: warning: format specifies type 'unsigned long' but
 the argument has type 'uint32_t' (aka 'unsigned int') [-Wformat]
                return makename("U%lu", id);
                                  ~~~   ^~
                                  %u

Signed-off-by: Alan Coopersmith <alan.coopersmith@oracle.com>