ebpf: fix mem_prot_alert anonymous file info

[AlonZivony]

1. Explain what the PR does

Anonymous files in mmap triggering mem_prot_alert got an incorrect file info, because it was not checked.
Fix it so there won't be file info in this case.

fix #3217

2. Explain how to test it

Ran it using the following script:

#include <stdio.h>
#include <stdlib.h>
#include <sys/mman.h>

int main() {
    size_t size = 4096; // Size of memory to allocate (in bytes)
    void* addr = NULL;  // Address at which to create the mapping

    // Allocate anonymous memory with write and execute permissions
    void* ptr = mmap(addr, size, PROT_WRITE | PROT_EXEC, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
    if (ptr == MAP_FAILED) {
        perror("mmap");
        exit(1);
    }

    if (munmap(ptr, size) == -1) {
        perror("munmap");
        exit(1);
    }

    return 0;
}
```c

[yanivagman]

LGTM