HSFS: avoid warning messages when compiling

hsi_nfs_inode.c: In function ‘nfs_alloc_inode’:
hsi_nfs_inode.c:264: warning: unused parameter ‘sb’
hsi_nfs_inode.c: In function ‘hsi_nfs_fhget’:
hsi_nfs_inode.c:392: warning: implicit declaration of function ‘unlock_new_inode’
hsi_nfs_inode.c:323: warning: unused variable ‘nfsi’
hsi_nfs_inode.c: In function ‘nfs_refresh_inode’:
hsi_nfs_inode.c:900: warning: unused variable ‘nfsi’
hsi_nfs_inode.c: In function ‘nfs_update_inode’:
hsi_nfs_inode.c:993: warning: unused variable ‘invalid’
hsi_nfs_inode.c:992: warning: unused variable ‘cur_isize’

Signed-off-by: Kinglong Mee <kinglongmee@gmail.com>