staging:lustre: Fix variable type declaration

Fix the following sparse warnings generated by AND-ing FMODE_* constant
with a normal integer.

drivers/staging/lustre/lustre/llite/file.c:102:32: warning: restricted
fmode_t degrades to integer

Signed-off-by: Dulshani Gunawardhana <dulshani.gunawardhana89@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>