imx8mp_evk: Pass kernel_addr_r

Currently, booting via bootstd fails because the kernel cannot be retrieved.
The reason for this is the lack of 'kernel_addr_r'.

Pass 'kernel_addr_r' to fix booting via bootstd.

Signed-off-by: Fabio Estevam <festevam@denx.de>
Reviewed-by: Peng Fan <peng.fan@nxp.com>

board/freescale/imx8mp_evk/imx8mp_evk.env

@@ -16,6 +16,7 @@ mmcroot=/dev/mmcblk1p2 rootwait rw
 mmcautodetect=yes
 mmcargs=setenv bootargs ${jh_clk} ${mcore_clk} console=${console} root=${mmcroot}
 prepare_mcore=setenv mcore_clk clk-imx8mp.mcore_booted
+kernel_addr_r=CONFIG_SYS_LOAD_ADDR
 loadimage=fatload mmc ${mmcdev}:${mmcpart} ${loadaddr} ${image}
 loadfdt=fatload mmc ${mmcdev}:${mmcpart} ${fdt_addr_r} ${fdtfile}
 mmcboot=echo Booting from mmc ...;