imx8mm_evk: Add Serial Download Protocol support

Add Serial Download Protocol support as it is a useful method to
load flash.bin to RAM and run it via 'uuu'.

With this patch, it is possible to start both U-Boot SPL and U-Boot
proper using the following 'uuu'command:

$ uuu -brun spl flash.bin

Based on a patch from Marek Vasut for the imx8mm-mx8menlo board.

Also, to fit the SPL binary into the internal RAM, select CONFIG_LTO
to reduce its size.

Signed-off-by: Fabio Estevam <festevam@denx.de>
Reviewed-by: Peng Fan <peng.fan@nxp.com>
diff --git a/configs/imx8mm_evk_defconfig b/configs/imx8mm_evk_defconfig
index 58b5e46..0797739 100644
--- a/configs/imx8mm_evk_defconfig
+++ b/configs/imx8mm_evk_defconfig
@@ -17,6 +17,7 @@
 CONFIG_SPL_DRIVERS_MISC=y
 CONFIG_SPL=y
 CONFIG_SYS_LOAD_ADDR=0x40480000
+CONFIG_LTO=y
 CONFIG_DISTRO_DEFAULTS=y
 CONFIG_FIT=y
 CONFIG_FIT_EXTERNAL_OFFSET=0x3000
@@ -39,6 +40,9 @@
 CONFIG_SYS_MMCSD_RAW_MODE_U_BOOT_SECTOR=0x300
 CONFIG_SPL_I2C=y
 CONFIG_SPL_POWER=y
+CONFIG_SPL_USB_HOST=y
+CONFIG_SPL_USB_GADGET=y
+CONFIG_SPL_USB_SDP_SUPPORT=y
 CONFIG_SPL_WATCHDOG=y
 CONFIG_SYS_MAXARGS=64
 CONFIG_SYS_CBSIZE=2048
@@ -51,6 +55,8 @@
 CONFIG_CMD_GPIO=y
 CONFIG_CMD_I2C=y
 CONFIG_CMD_MMC=y
+CONFIG_CMD_USB_SDP=y
+CONFIG_CMD_USB_MASS_STORAGE=y
 CONFIG_CMD_CACHE=y
 CONFIG_CMD_REGULATOR=y
 CONFIG_CMD_EXT4_WRITE=y
@@ -81,9 +87,13 @@
 CONFIG_PHY_GIGE=y
 CONFIG_FEC_MXC=y
 CONFIG_MII=y
+CONFIG_SPL_PHY=y
+CONFIG_SPL_NOP_PHY=y
 CONFIG_PINCTRL=y
 CONFIG_SPL_PINCTRL=y
 CONFIG_PINCTRL_IMX8M=y
+CONFIG_POWER_DOMAIN=y
+CONFIG_IMX8M_POWER_DOMAIN=y
 CONFIG_DM_PMIC=y
 CONFIG_SPL_DM_PMIC_PCA9450=y
 CONFIG_DM_REGULATOR=y
@@ -98,4 +108,15 @@
 CONFIG_SYSRESET_PSCI=y
 CONFIG_SYSRESET_WATCHDOG=y
 CONFIG_DM_THERMAL=y
+CONFIG_USB=y
+CONFIG_USB_EHCI_HCD=y
+CONFIG_MXC_USB_OTG_HACTIVE=y
+# CONFIG_USB_STORAGE is not set
+CONFIG_USB_GADGET=y
+CONFIG_USB_GADGET_MANUFACTURER="FSL"
+CONFIG_USB_GADGET_VENDOR_NUM=0x0525
+CONFIG_USB_GADGET_PRODUCT_NUM=0xa4a5
+CONFIG_CI_UDC=y
+CONFIG_SDP_LOADADDR=0x40400000
+CONFIG_USB_GADGET_DOWNLOAD=y
 CONFIG_IMX_WATCHDOG=y