configs/polyhex_debix_model_a_defconfig: Remove BR2_PACKAGE_HOST_IMX_MKIMAGE

The BR2_PACKAGE_HOST_IMX_MKIMAGE is only needed when the NXP U-Boot
version is used.

polyhex_debix_model_a_defconfig uses mainline U-Boot, which builds flash.bin
directly, without using the NXP imx-mkimage tool.

Remove such unneeded package.

Signed-off-by: Fabio Estevam <festevam@gmail.com>
Signed-off-by: Julien Olivain <ju.o@free.fr>

configs/polyhex_debix_model_a_defconfig

@@ -42,6 +42,5 @@ BR2_TARGET_UBOOT_FORMAT_CUSTOM=y
 BR2_TARGET_UBOOT_FORMAT_CUSTOM_NAME="flash.bin"
 BR2_TARGET_UBOOT_SPL=y
 BR2_PACKAGE_HOST_GENIMAGE=y
-BR2_PACKAGE_HOST_IMX_MKIMAGE=y
 BR2_PACKAGE_HOST_UBOOT_TOOLS=y
 BR2_PACKAGE_HOST_UBOOT_TOOLS_FIT_SUPPORT=y