Fix mislabelled mul64_imm and mul64_reg (#573)

* Fix mislabelled mul64_imm and mul64_reg

MUL64_IMM and MUL64_REG opcodes were both mislabelled in the comments as div64 which also stated that they perform an operation equivalent `/=`. This commit accurately labels them both as mul64 and performing an operation equivalent to `*=`.

* Fix comments for neg64

neg64 was also mislabelled as requiring two operands `dst, src` when it only takes in `dst`. This is now fixed.

src/ebpf.rs

@@ -322,9 +322,9 @@ pub const ADD64_REG: u8 = BPF_ALU64 | BPF_X | BPF_ADD;
 pub const SUB64_IMM: u8 = BPF_ALU64 | BPF_K | BPF_SUB;
 /// BPF opcode: `sub64 dst, src` /// `dst -= src`.
 pub const SUB64_REG: u8 = BPF_ALU64 | BPF_X | BPF_SUB;
-/// BPF opcode: `div64 dst, imm` /// `dst /= imm`.
+/// BPF opcode: `mul64 dst, imm` /// `dst *= imm`.
 pub const MUL64_IMM: u8 = BPF_ALU64 | BPF_K | BPF_MUL;
-/// BPF opcode: `div64 dst, src` /// `dst /= src`.
+/// BPF opcode: `mul64 dst, src` /// `dst *= src`.
 pub const MUL64_REG: u8 = BPF_ALU64 | BPF_X | BPF_MUL;
 /// BPF opcode: `div64 dst, imm` /// `dst /= imm`.
 pub const DIV64_IMM: u8 = BPF_ALU64 | BPF_K | BPF_DIV;
@@ -346,7 +346,7 @@ pub const LSH64_REG: u8 = BPF_ALU64 | BPF_X | BPF_LSH;
 pub const RSH64_IMM: u8 = BPF_ALU64 | BPF_K | BPF_RSH;
 /// BPF opcode: `rsh64 dst, src` /// `dst >>= src`.
 pub const RSH64_REG: u8 = BPF_ALU64 | BPF_X | BPF_RSH;
-/// BPF opcode: `neg64 dst, imm` /// `dst = -dst`.
+/// BPF opcode: `neg64 dst` /// `dst = -dst`.
 pub const NEG64: u8 = BPF_ALU64 | BPF_NEG;
 /// BPF opcode: `mod64 dst, imm` /// `dst %= imm`.
 pub const MOD64_IMM: u8 = BPF_ALU64 | BPF_K | BPF_MOD;