configs/kontron_bl_imx8mm_defconfig: U-Boot requires OpenSSL

Fixes:
https://gitlab.com/buildroot.org/buildroot/-/jobs/2103784267

Signed-off-by: Giulio Benetti <giulio.benetti@benettiengineering.com>
Reviewed-by: Marcus Hoffmann <marcus.hoffmann@othermo.de>
Signed-off-by: Yann E. MORIN <yann.morin.1998@free.fr>

configs/kontron_bl_imx8mm_defconfig

@@ -45,6 +45,7 @@ BR2_TARGET_UBOOT_BOARD_DEFCONFIG="kontron-sl-mx8mm"
 BR2_TARGET_UBOOT_NEEDS_DTC=y
 BR2_TARGET_UBOOT_NEEDS_PYTHON3=y
 BR2_TARGET_UBOOT_NEEDS_PYLIBFDT=y
+BR2_TARGET_UBOOT_NEEDS_OPENSSL=y
 BR2_TARGET_UBOOT_NEEDS_ATF_BL31=y
 BR2_TARGET_UBOOT_NEEDS_ATF_BL31_BIN=y
 BR2_TARGET_UBOOT_NEEDS_IMX_FIRMWARE=y