Introduce imx6q-sabresd_qt5_defconfig that supports the opensource
Etnaviv graphical stack.

This defconfig provides a way to quickly test some graphical applications,
such as kmscube, qt5, glmark2.

Currently kernel mainline exhibits issues when running cpufreq as ondemand
governor on mx6, so add a linux fragment that disables such option for the
time being.

Signed-off-by: Fabio Estevam <festevam@gmail.com>
[Arnout:
 - Add Fabio to DEVELOPERS
 - Rename linux config fragment to linux_qt5.fragment
 - Add comment to linux_qt5.fragment why it is needed
 - Add explicit CONFIG_CPU_FREQ_DEFAULT_GOV_PERFORMANCE=y to it
 - Reorder defconfig entries to they match imx6q-sabresd_defconfig
 - Remove strace and host-uboot-tools, neither seems to be needed
 - Drop BR2_PACKAGE_QT5BASE_LICENSE_APPROVED, it no longer exists
 - Replace BR2_TARGET_ROOTFS_EXT2_BLOCKS with BR2_TARGET_ROOTFS_EXT2_SIZE
 - Regenerate .gitlab-ci.yml]
Signed-off-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>