APF: drop multicast ICMPv6 while in doze mode

Some WiFi hotspots send excessive multicast IPv6 ping requests which
cause considerable power drain. Thus, drop all multicast ICMPv6 ping
requests while the device is in doze mode.

Bug: 66930077
Test: runtest -x tests/net/java/android/net/apf/ApfTest.java
Test: manual - compared generated APF bytecode using apf_disassembler
Test: manual - force idle mode while sending multicast pings to device
Change-Id: I25dbf99985cf4413b4d0e3920d281fe6d663197a