configs/beagleboneai: switch to Bootlin glibc stable toolchain

Signed-off-by: Peter Korsgaard <peter@korsgaard.com>
Signed-off-by: Julien Olivain <ju.o@free.fr>

configs/beagleboneai_defconfig

@@ -1,6 +1,8 @@
 BR2_arm=y
 BR2_cortex_a15=y
-BR2_PACKAGE_HOST_LINUX_HEADERS_CUSTOM_6_12=y
+BR2_TOOLCHAIN_EXTERNAL=y
+BR2_TOOLCHAIN_EXTERNAL_BOOTLIN=y
+BR2_TOOLCHAIN_EXTERNAL_BOOTLIN_ARMV7_EABIHF_GLIBC_STABLE=y
 BR2_GLOBAL_PATCH_DIR="board/beagleboard/beagleboneai/patches"
 BR2_DOWNLOAD_FORCE_CHECK_HASHES=y
 BR2_SYSTEM_DHCP="eth0"