x86: 8K stacks by default

Switch back to 8K stacks as the safer default. Out-of-memory
situations are less problematic than silent and hard to debug
stack corruption.
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

arch/x86/Kconfig.debug

@@ -118,7 +118,6 @@ config DEBUG_NX_TEST
 config 4KSTACKS
 	bool "Use 4Kb for kernel stacks instead of 8Kb"
 	depends on X86_32
-	default y
 	help
 	  If you say Y here the kernel will use a 4Kb stacksize for the
 	  kernel stack attached to each process/thread. This facilitates