dm: include <dm/util.h> from drivers/core/util.c
Fix sparse warnings "... was not declared. Should it be static?"
Also, fix redefinition of dm_warn/dm_dbg.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>