configs/kontron_pitx_imx8m_defconfig: add BR2_GLOBAL_PATCH_DIR
Add config option to set the board specific GLOBAL_PATCH_DIR.
Fixes: https://gitlab.com/buildroot.org/buildroot/-/jobs/2750360083
Signed-off-by: Heiko Thiery <heiko.thiery@gmail.com>
Signed-off-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>