get rid of files_defer_init()

the only thing it's doing these days is calculation of
upper limit for fs.nr_open sysctl and that can be done
statically

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

diff --cc fs/file.c
Simple merge

diff --cc fs/file_table.c
Simple merge

diff --cc include/linux/fdtable.h
Simple merge