tools: fix scan-build warnings in scmp_bpf_disasm

Delete the unused variable 'len' from scmp_bpf_disasm.

scan-build identified the following two warnings:

    scmp_bpf_disasm.c:304:10: warning: Although the value stored to 'len'
    is used in the enclosing expression, the value is never actually read
    from 'len'
            while ((len = fread(&bpf, sizeof(bpf), 1, file))) {

    scmp_bpf_disasm.c:441:10: warning: Although the value stored to 'len' is
    used in the enclosing expression, the value is never actually read from
    'len'
            while ((len = fread(&bpf, sizeof(bpf), 1, file))) {

Signed-off-by: Tom Hromatka <[email protected]>
Signed-off-by: Paul Moore <[email protected]>

tools/scmp_bpf_disasm.c

@@ -294,14 +294,13 @@ static void bpf_decode_args(const bpf_instr_raw *bpf, unsigned int line)
 static int bpf_decode(FILE *file)
 {
  unsigned int line = 0;
- size_t len;
  bpf_instr_raw bpf;
 
  /* header */
  printf(" line OP JT JF K\n");
  printf("=================================\n");
 
- while ((len = fread(&bpf, sizeof(bpf), 1, file))) {
+ while (fread(&bpf, sizeof(bpf), 1, file)) {
  /* convert the bpf statement */
  bpf.code = ttoh16(arch, bpf.code);
  bpf.k = ttoh32(arch, bpf.k);
@@ -430,15 +429,14 @@ static void bpf_dot_decode_args(const bpf_instr_raw *bpf, unsigned int line)
 static int bpf_dot_decode(FILE *file)
 {
  unsigned int line = 0;
- size_t len;
  bpf_instr_raw bpf;
  int prev_class = 0;
 
  /* header */
  printf("digraph {\n");
  printf("\tstart[shape=\"box\", style=rounded];\n");
 
- while ((len = fread(&bpf, sizeof(bpf), 1, file))) {
+ while (fread(&bpf, sizeof(bpf), 1, file)) {
  /* convert the bpf statement */
  bpf.code = ttoh16(arch, bpf.code);
  bpf.k = ttoh32(arch, bpf.k);