imx: imx93_evk: switch to BOOTSTD

Switch to support BOOTSTD with a bsp bootcmd as fallback.
Move the env to imx93_evk.env

Signed-off-by: Peng Fan <peng.fan@nxp.com>
diff --git a/arch/arm/mach-imx/imx9/Kconfig b/arch/arm/mach-imx/imx9/Kconfig
index 54c6b11..c525460 100644
--- a/arch/arm/mach-imx/imx9/Kconfig
+++ b/arch/arm/mach-imx/imx9/Kconfig
@@ -47,6 +47,8 @@
 	select OF_BOARD_FIXUP
 	select IMX93
 	imply OF_UPSTREAM
+	imply BOOTSTD_FULL
+	imply BOOTSTD_BOOTCOMMAND
 
 config TARGET_IMX93_VAR_SOM
 	bool "imx93_var_som"