Have cifs_write take a cifsFileInfo pointer instead of a filp. Since
cifsFileInfo holds references on the dentry, and that holds one to
the inode, we can eliminate some unneeded NULL pointer checks.
Signed-off-by: Jeff Layton <jlayton@redhat.com> Reviewed-by: Suresh Jayaraman <sjayaraman@suse.de> Acked-by: Dave Kleikamp <shaggy@linux.vnet.ibm.com> Signed-off-by: Steve French <sfrench@us.ibm.com>