include: posix: fcntl: add O_TRUNC flags for posix open()

introduction of O_TRUNC flag has conflict with libc flags,
so realtered posix open flags based on the commit
499a6339 ("posix: device_io: use mode argument correctly in open()")

Signed-off-by: Chris Friedt <cfriedt@tenstorrent.com>
Signed-off-by: Karthikeyan Krishnasamy <karthikeyan@linumiz.com>