docs/features: parisc implements tracehook

Since commit 64e2a42bca ("parisc: Add ARCH_TRACEHOOK and regset
support") in v4.7, parisc selects HAVE_ARCH_TRACEHOOK, so update its
entry in Documentation/features from TODO to ok.

Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: "James E.J. Bottomley" <jejb@parisc-linux.org>
Cc: Helge Deller <deller@gmx.de>
Cc: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>

Documentation/features/core/tracehook/arch-support.txt

@@ -25,7 +25,7 @@
     |     mn10300: |  ok  |
     |       nios2: |  ok  |
     |    openrisc: |  ok  |
-    |      parisc: | TODO |
+    |      parisc: |  ok  |
     |     powerpc: |  ok  |
     |        s390: |  ok  |
     |       score: | TODO |