bpf, docs: Fix definition of BPF_NEG operation

Instruction is an arithmetic negative, not a bitwise inverse.
Signed-off-by: Dave Thaler <dthaler@microsoft.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: David Vernet <void@manifault.com>
Link: https://lore.kernel.org/bpf/20230627213912.951-1-dthaler1968@googlemail.com

Documentation/bpf/instruction-set.rst

@@ -165,7 +165,7 @@ BPF_OR    0x40   dst \|= src
 BPF_AND   0x50   dst &= src
 BPF_LSH   0x60   dst <<= (src & mask)
 BPF_RSH   0x70   dst >>= (src & mask)
-BPF_NEG   0x80   dst = ~src
+BPF_NEG   0x80   dst = -src
 BPF_MOD   0x90   dst = (src != 0) ? (dst % src) : dst
 BPF_XOR   0xa0   dst ^= src
 BPF_MOV   0xb0   dst = src