drm/i915: set O_LARGEFILE in __create_shmem()

drm/i915: set O_LARGEFILE in __create_shmem()

Without O_LARGEFILE, file->f_op->write_iter calls
generic_write_check_limits(), which enforces a 2GB (MAX_NON_LFS) limit,
causing -EFBIG on large writes.

In shmem_pwrite(), this error is later masked as -EIO due to the error
handling order, leading to igt failures like gen9_exec_parse(bb-large).

Set O_LARGEFILE in __create_shmem() to prevent -EFBIG on large writes.

Reported-by: kernel test robot <oliver.sang@intel.com>
Closes: https://lore.kernel.org/oe-lkp/202508081029.343192ec-lkp@intel.com
Fixes: 048832a3f400 ("drm/i915: Refactor shmem_pwrite() to use kiocb and write_iter")
Signed-off-by: Taotao Chen <chentaotao@didiglobal.com>
Reviewed-by: Andi Shyti <andi.shyti@linux.intel.com>
Signed-off-by: Andi Shyti <andi.shyti@linux.intel.com>
Link: https://lore.kernel.org/r/20250822030651.28099-1-chentaotao@didiglobal.com