configs/imx6-sabresd_qt5: add missing dependency on host-openssl

host-openssl is needed to build the Linux kernel. This is the same
issue that was fixed in commit
5dac3b9b ("configs/imx6-sabresd: needs
host-openssl for the Linux kernel build") for the minimal defconfig
for the same board.

Fixes:

  https://gitlab.com/buildroot.org/buildroot/-/jobs/123771070



Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>