selftests: openat2: Fix testing failure for O_LARGEFILE flag

The openat2 test suite fails on ARM64 because the definition of
O_LARGEFILE is different on ARM64. Fix the problem by defining
the correct O_LARGEFILE definition on ARM64.

"openat2 unexpectedly returned # 3['.../tools/testing/selftests/openat2']
with 208000 (!= 208000)
not ok 102 openat2 with incompatible flags (O_PATH | O_LARGEFILE) fails
with -22 (Invalid argument)"

Fixed change log to improve formatting and clarity:
Shuah Khan <skhan@linuxfoundation.org>

Signed-off-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Reviewed-by: Aleksa Sarai <cyphar@cyphar.com>
Acked-by: Christian Brauner <christian.brauner@ubuntu.com>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>