bpf: make inode code explicitly non-modular

The Kconfig currently controlling compilation of this code is:

init/Kconfig:config BPF_SYSCALL
init/Kconfig:   bool "Enable bpf() system call"

...meaning that it currently is not being built as a module by anyone.

Lets remove the couple traces of modular infrastructure use, so that
when reading the driver there is no doubt it is builtin-only.

Note that MODULE_ALIAS is a no-op for non-modular code.

We replace module.h with init.h since the file does use __init.

Cc: Alexei Starovoitov <ast@kernel.org>
Cc: netdev@vger.kernel.org
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>