module: Fully remove the kernel_module_from_file hook

Remove remaining kernel_module_from_file hook left by commit
a1db7420

 ("module: replace copy_module_from_fd with kernel version")

Signed-off-by: Mickaël Salaün <mic@digikod.net>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Acked-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
Signed-off-by: James Morris <james.l.morris@oracle.com>