Remove old create flag that was used for choosing the access mode.
New flag 'oflag' determines the mode in which the file has to be
opened, i.e., read, write or both. Applications shall specify exactly
one of the first three values (file access modes) below in the value
of oflag:

O_RDONLY: Open for reading only
O_WRONLY: Open for writing only
O_RDWR: Open for reading and writing