bpf: Remove unused variable in nsim_bpf

Clang warns:

drivers/net/netdevsim/bpf.c:557:30: error: unused variable 'state'
[-Werror,-Wunused-variable]
        struct nsim_bpf_bound_prog *state;
                                    ^
1 error generated.

The declaration should have been removed in commit b07ade27 ("bpf:
pass translate() as a callback and remove its ndo_bpf subcommand").

Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>
Acked-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Acked-by: Quentin Monnet <quentin.monnet@netronome.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>