atf: fix build failure due to optee binary not exist
When optee enabled in DISTRO_FEATURES, optee-os-qoriq is added as
DEPENDS, and atf tries to find optee binary under ${DEPLOY_DIR_IMAGE}.
This has issue when do_deploy task of optee-os-qoriq does not run
before atf's do_compile.
Switch to find optee binary under ${RECIPE_SYSROOT} instead of
${DEPLOY_DIR_IMAGE}.
Steps to reproduce the issue:
$ echo 'DISTRO_FEATURES_append = " optee"' >>conf/local.conf
$ bitbake -c cleansstate atf optee-os-qoriq
$ bitbake -c install optee-os-qoriq
$ bitbake -c compile atf
| Building lx2160ardb
| Makefile:633: *** 'BL32=.../tmp/deploy/images/lx2160ardb/optee/tee_lx2160ardb.bin'
| was specified, but '.../tmp/deploy/images/lx2160ardb/optee/tee_lx2160ardb.bin'
| does not exist. Stop.
| make: *** Waiting for unfinished jobs....
