fix: ebpf program build warnings - #619

/git/eupf/cmd/ebpf/xdp/n3n6_entrypoint.c:114:60: warning: passing 'volatile __u64 *' (aka 'volatile unsigned long long *') to parameter of type '__u64 *' (aka 'unsigned long long *') discards qualifiers [-Wincompatible-pointer-types-discards-qualifiers]
    if (XDP_DROP == limit_rate_sliding_window(packet_size, &qer->dl_start, qer->dl_maximum_bitrate))
                                                           ^~~~~~~~~~~~~~
./xdp/qer.h:67:98: note: passing argument to parameter 'windows_start' here
static __always_inline enum xdp_action limit_rate_sliding_window(const __u64 packet_size, __u64 *windows_start, const __u64 rate) {
                                                                                                 ^
/git/eupf/cmd/ebpf/xdp/n3n6_entrypoint.c:177:60: warning: passing 'volatile __u64 *' (aka 'volatile unsigned long long *') to parameter of type '__u64 *' (aka 'unsigned long long *') discards qualifiers [-Wincompatible-pointer-types-discards-qualifiers]
    if (XDP_DROP == limit_rate_sliding_window(packet_size, &qer->dl_start, qer->dl_maximum_bitrate))
                                                           ^~~~~~~~~~~~~~
./xdp/qer.h:67:98: note: passing argument to parameter 'windows_start' here
static __always_inline enum xdp_action limit_rate_sliding_window(const __u64 packet_size, __u64 *windows_start, const __u64 rate) {
                                                                                                 ^
/git/eupf/cmd/ebpf/xdp/n3n6_entrypoint.c:309:60: warning: passing 'volatile __u64 *' (aka 'volatile unsigned long long *') to parameter of type '__u64 *' (aka 'unsigned long long *') discards qualifiers [-Wincompatible-pointer-types-discards-qualifiers]
    if (XDP_DROP == limit_rate_sliding_window(packet_size, &qer->ul_start, qer->ul_maximum_bitrate))
                                                           ^~~~~~~~~~~~~~
./xdp/qer.h:67:98: note: passing argument to parameter 'windows_start' here
static __always_inline enum xdp_action limit_rate_sliding_window(const __u64 packet_size, __u64 *windows_start, const __u64 rate) {
                                                                                                 ^
3 warnings generated.