configs: am335x_boneblack_vboot_defconfig: Add DM for SPI and Flash devices

This patch adds SPI and SPI_FLASH DM support for verified boot on
TI AM335 chipsets. The following compile warning is removed:

===================== WARNING ======================
This board does not use CONFIG_DM_SPI_FLASH. Please update
the board to use CONFIG_SPI_FLASH before the v2019.07 release.
Failure to update by the deadline may result in board removal.
See doc/driver-model/MIGRATION.txt for more info.
====================================================

Built and tested on AM335x device (BeagleboneBlack).

Signed-off-by: Suniel Mahesh <sunil.m@techveda.org>
diff --git a/configs/am335x_boneblack_vboot_defconfig b/configs/am335x_boneblack_vboot_defconfig
index a6c32ac..a7fcde6 100644
--- a/configs/am335x_boneblack_vboot_defconfig
+++ b/configs/am335x_boneblack_vboot_defconfig
@@ -43,6 +43,7 @@
 CONFIG_DM_MMC=y
 CONFIG_MMC_OMAP_HS=y
 # CONFIG_SPL_DM_MMC is not set
+CONFIG_DM_SPI_FLASH=y
 CONFIG_SPI_FLASH=y
 CONFIG_SF_DEFAULT_SPEED=24000000
 CONFIG_SPI_FLASH_WINBOND=y
@@ -51,6 +52,7 @@
 CONFIG_MII=y
 CONFIG_DRIVER_TI_CPSW=y
 CONFIG_SPI=y
+CONFIG_DM_SPI=y
 CONFIG_OMAP3_SPI=y
 CONFIG_TIMER=y
 CONFIG_OMAP_TIMER=y