sound/oss/awe_wave.c: fix a compile warning

This patch fixes the following compile warning:

<-- snip -->

...
CC sound/oss/awe_wave.o
In file included from sound/oss/os.h:31,

                 from sound/oss/sound_config.h:21,
                 from sound/oss/awe_wave.c:37:

include/linux/soundcard.h:195:1: warning: "_PATCHKEY" redefined
In file included from sound/oss/awe_wave.c:30:
include/linux/awe_voice.h:33:1: warning: this is the location of the previous definition
...

<-- snip -->

@@ -29,10 +29,6 @@
 #define SAMPLE_TYPE_AWE32	0x20
 #endif
 
-#ifndef _PATCHKEY
-#define _PATCHKEY(id) ((id<<8)|0xfd)
-#endif
-
 /*----------------------------------------------------------------
  * patch information record
  *----------------------------------------------------------------*/