pcsp - Don't build pcspkr when snd-pcsp is enabled

- Update CREDITS with the pc-speaker driver authors.
- Prevent pcspkr from being built together with snd-pcsp.
  Both pcspkr and snd-pcsp use the same platform driver name "pcspkr".

Signed-off-by: Stas Sergeev <stsp@aknet.ru>
diff --git a/CREDITS b/CREDITS
index da0a56e..8fec7b3 100644
--- a/CREDITS
+++ b/CREDITS
@@ -403,6 +403,8 @@
 N: Erik Inge Bolsø
 E: knan@mo.himolde.no
 D: Misc kernel hacks
+D: Updated PC speaker driver for 2.3
+S: Norway
 
 N: Andreas E. Bombe
 E: andreas.bombe@munich.netsurf.de
@@ -3116,6 +3118,12 @@
 S: Sunnyvale, California 94088-4132
 S: USA
 
+N: Stas Sergeev
+E: stsp@users.sourceforge.net
+D: PCM PC-Speaker driver
+D: misc fixes
+S: Russia
+
 N: Simon Shapiro
 E: shimon@i-Connect.Net
 W: http://www.-i-Connect.Net/~shimon