bpf: remove stubs for cBPF from arch code

Remove the dummy bpf_jit_compile() stubs for eBPF JITs and make
that a single __weak function in the core that can be overridden
similarly to the eBPF one. Also remove stale pr_err() mentions
of bpf_jit_compile.

Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

arch/powerpc/net/bpf_jit_comp64.c

@@ -961,8 +961,6 @@ common_load:
 	return 0;
 }
 
-void bpf_jit_compile(struct bpf_prog *fp) { }
-
 struct bpf_prog *bpf_int_jit_compile(struct bpf_prog *fp)
 {
 	u32 proglen;