[kernel] Add spam logging to trace mailbox calls

Added a new IPC log category, and logging of mailbox calls in it. Also added
some logs in init's service locator to help track down the bug fixed in the
previous commit.

src/libraries/j6/include/j6/tables/log_areas.inc

@@ -2,10 +2,11 @@ LOG(apic,   info)
 LOG(boot,   info)
 LOG(device, spam)
 LOG(irq,    info)
-LOG(memory, info)
-LOG(objs,   info)
+LOG(memory, verbose)
+LOG(objs,   spam)
 LOG(paging, info)
-LOG(sched,  info)
-LOG(syscall,info)
+LOG(sched,  verbose)
+LOG(syscall,verbose)
 LOG(task,   verbose)
 LOG(timer,  info)
+LOG(ipc,    spam)