Fix UTS_MACHINE

Remove the default for UTS_MACHINE, it gets set in
include/linux/compile.h, just as UTS_RELEASE.

(noticed by David Gibson)

include/linux/uts.h

@@ -8,10 +8,6 @@
 #define UTS_SYSNAME "Linux"
 #endif
 
-#ifndef UTS_MACHINE
-#define UTS_MACHINE "unknown"
-#endif
-
 #ifndef UTS_NODENAME
 #define UTS_NODENAME "(none)"	/* set by sethostname() */
 #endif