bpf: Remove arch_unprotect_bpf_trampoline()

Last user of arch_unprotect_bpf_trampoline() was removed by
commit 187e2af0 ("bpf: struct_ops supports more than one page for
trampolines.")

Remove arch_unprotect_bpf_trampoline()

Reported-by: Daniel Borkmann <daniel@iogearbox.net>
Fixes: 187e2af0 ("bpf: struct_ops supports more than one page for trampolines.")
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Link: https://lore.kernel.org/r/42c635bb54d3af91db0f9b85d724c7c290069f67.1710574353.git.christophe.leroy@csgroup.eu


Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>