[riscv-pmp] Pmp_hart_has_privs local variable name easily misunderstood
Additional information:
```c
// int => bool 
static int pmp_is_in_range(CPURISCVState *env, int pmp_index,
                           target_ulong addr);

bool pmp_hart_has_privs(CPURISCVState *env, target_ulong addr,
                        target_ulong size, pmp_priv_t privs,
                        pmp_priv_t *allowed_privs, target_ulong mode)
{
    int i = 0;
    int pmp_size = 0;
    // easily misunderstood local variable 
    target_ulong s = 0;
    target_ulong e = 0;

    for (i = 0; i < MAX_RISCV_PMPS; i++) {
        s = pmp_is_in_range(env, i, addr);
        e = pmp_is_in_range(env, i, addr + pmp_size - 1);

        /* partially inside */
        if ((s + e) == 1) {
          
        }

        /* fully inside */
        if ((s + e) == 2) {
```