x86/boot: Simplify the detect_memory*() control flow

The return values of these functions are not used - so simplify the functions.

No change in functionality.

[ mingo: Simplified the changelog. ]

Suggested: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Jordan Borgner <mail@jordan-borgner.de>
Cc: Borislav Petkov <bp@alien8.de>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20181102145622.zjx2t3mdu3rv6sgy@JordanDesktop
Signed-off-by: Ingo Molnar <mingo@kernel.org>

arch/x86/boot/boot.h

@@ -309,7 +309,7 @@ void query_edd(void);
 void __attribute__((noreturn)) die(void);
 
 /* memory.c */
-int detect_memory(void);
+void detect_memory(void);
 
 /* pm.c */
 void __attribute__((noreturn)) go_to_protected_mode(void);