dm: mmc: Enable DM_MMC_OPS by default with DM_MMC

These two options go together and it is best to do the conversion in one
step. So enable DM_MMC_OPS by default if DM_MMC is enabled.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/configs/p2571_defconfig b/configs/p2571_defconfig
index fece81b..1375b52 100644
--- a/configs/p2571_defconfig
+++ b/configs/p2571_defconfig
@@ -32,6 +32,7 @@
 CONFIG_DFU_MMC=y
 CONFIG_DFU_RAM=y
 CONFIG_DFU_SF=y
+# CONFIG_DM_MMC_OPS is not set
 CONFIG_SPI_FLASH=y
 CONFIG_SPI_FLASH_WINBOND=y
 CONFIG_SYS_NS16550=y