xtensa: Fix spelling/grammar in comment

Change 'excpetion' to 'exception', 'handeled' to 'handled' and 'the the'
to 'the'.
Signed-off-by: Chris Packham <chris.packham@alliedtelesis.co.nz>
Message-Id: <20200525230413.15551-1-chris.packham@alliedtelesis.co.nz>
Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>

arch/xtensa/kernel/entry.S

@@ -959,14 +959,14 @@ ENDPROC(unrecoverable_exception)
  * of the proper size instead.
  *
  * This algorithm simply backs out the register changes started by the user
- * excpetion handler, makes it appear that we have started a window underflow
+ * exception handler, makes it appear that we have started a window underflow
  * by rotating the window back and then setting the old window base (OWB) in
  * the 'ps' register with the rolled back window base. The 'movsp' instruction
  * will be re-executed and this time since the next window frames is in the
  * active AR registers it won't cause an exception.
  *
  * If the WindowUnderflow code gets a TLB miss the page will get mapped
- * the the partial windeowUnderflow will be handeled in the double exception
+ * the partial WindowUnderflow will be handled in the double exception
  * handler.
  *
  * Entry condition: