configs/mx6sx_udoo_neo: select host-openssl for the Linux kernel build

configs/mx6sx_udoo_neo: select host-openssl for the Linux kernel build

Select BR2_LINUX_KERNEL_NEEDS_HOST_OPENSSL=y to fix the following
build error:

scripts/extract-cert.c:21:25: fatal error: openssl/bio.h: No such file or directory
 #include <openssl/bio.h>

Fixes:
 https://gitlab.com/buildroot.org/buildroot/-/jobs/831421063

Signed-off-by: Fabio Estevam <festevam@gmail.com>
Reviewed-by: Marcin Niestroj <m.niestroj@grinn-global.com>
Tested-by: Marcin Niestroj <m.niestroj@grinn-global.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>