MPC824x: remove obsolete "PN62" board

The MPC824x processors have long reached EOL, and the PN62 board has
not seen any board-specific updates for more than a decade.  It is now
causing build issues.  Instead of wasting time on things nobody is
interested in any more, we rather drop this board.

Signed-off-by: Wolfgang Denk <wd@denx.de>
Cc: Wolfgang Grandegger <wg@grandegger.com>
cc: Tom Rini <trini@ti.com>
diff --git a/CREDITS b/CREDITS
index 3b657e9..52f289e 100644
--- a/CREDITS
+++ b/CREDITS
@@ -143,7 +143,7 @@
 
 N: Dr. Wolfgang Grandegger
 E: wg@denx.de
-D: Support for Interphase 4539 T1/E1/J1 PMC, PN62, CCM, SCM boards
+D: Support for Interphase 4539 T1/E1/J1 PMC, CCM, SCM boards
 W: www.denx.de
 
 N: Peter Figuli