[kernel] Spell 'cancellation' correctly.

TEST: No behavior change
Change-Id: I5431b14df25fa6ef7cedea65035898aebc9ca212
diff --git a/kernel/object/timer_dispatcher.cpp b/kernel/object/timer_dispatcher.cpp
index 49e9905..7387421 100644
--- a/kernel/object/timer_dispatcher.cpp
+++ b/kernel/object/timer_dispatcher.cpp
@@ -97,15 +97,15 @@
     deadline_ = deadline;
     slack_ = slack;
 
-    // If we're imminently awaiting a timer callback due to a prior cancelation request,
-    // let the callback take care of restarting the timer too so everthing happens in the
+    // If we're imminently awaiting a timer callback due to a prior cancellation request,
+    // let the callback take care of restarting the timer too so everything happens in the
     // right sequence.
     if (cancel_pending_)
         return ZX_OK;
 
     // We need to ref-up because the timer and the dpc don't understand
     // refcounted objects. The Release() is called either in OnTimerFired()
-    // or in the complicated cancelation path above.
+    // or in the complicated cancellation path above.
     AddRef();
 
     // We must ensure that the timer callback (running in interrupt context,
diff --git a/kernel/syscalls/channel.cpp b/kernel/syscalls/channel.cpp
index 8e2014d..65385c9 100644
--- a/kernel/syscalls/channel.cpp
+++ b/kernel/syscalls/channel.cpp
@@ -375,7 +375,7 @@
 
     // TODO(ZX-970): ktrace channel calls; maybe two traces, maybe with txid.
 
-    // Write message and wait for reply, deadline, or cancelation
+    // Write message and wait for reply, deadline, or cancellation
     ktl::unique_ptr<MessagePacket> reply;
     status = channel->Call(up->get_koid(), ktl::move(msg), deadline, &reply);
     if (status != ZX_OK)