toolchain: move sysroot to host dir

* Drop the BR2_STAGING_DIR option
* Hardcode STAGING_DIR to $(HOST_DIR)/usr/TUPLE/sysroot

Signed-off-by: Gustavo Zacarias <gustavo@zacarias.com.ar>
Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>
3 files changed