configs/mx6udoo: select host-openssl for the Linux kernel build

configs/mx6udoo: 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/831421064

Signed-off-by: Fabio Estevam <[email protected]>
Reviewed-by: Marcin Niestroj <[email protected]>
Tested-by: Marcin Niestroj <[email protected]>
Signed-off-by: Thomas Petazzoni <[email protected]>