staging: lustre: use linux/statfs.h instead of asm/statfs.h

Fix the following checkpatch warning:

drivers/staging/lustre/lustre/include/linux/lustre_lite.h:46:
WARNING:INCLUDE_LINUX: Use #include <linux/statfs.h> instead of <asm/statfs.h>

Signed-off-by: Mike Rapoport <mike.rapoport@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>