staging: lustre: Fix variable type declaration after refactoring

A recent clean-up declared och_flags as a int rather than fmode_t. This
lead to the following sparse warning:

drivers/staging/lustre/lustre/llite/file.c:106:30: warning: restricted
fmode_t degrades to integer

This patch fixes this issue.

Fixes: 0a120099 ("staging: lustre: cleanup lustre_lib.h")
Signed-off-by: Quentin Lambert <lambert.quentin@gmail.com>
Acked-by: James Simmons <jsimmons@infradead.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>