LU-12355 llite: vfs atomic_open change with FMODE_CREATED

LU-12355 llite: vfs atomic_open change with FMODE_CREATED

Kernel 4.19 introduced FMODE_CREATED and switched to it while
the last argument to vfs atomic_open was removed and the f_mode
flags are used to indicate the created state on return.

Linux-commit: 73a09dd94377e4b186b300bd5461920710c7c3d5

Test-Parameters: trivial
Change-Id: I26d4aadb123bb1d1bc0aa1d78a64a75b94276ffb
Signed-off-by: Shaun Tancheff <stancheff@cray.com>
Reviewed-on: https://review.whamcloud.com/35020
Tested-by: Jenkins
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: James Simmons <uja.ornl@yahoo.com>
Reviewed-by: Thomas Stibor <t.stibor@gsi.de>
Reviewed-by: Oleg Drokin <green@whamcloud.com>