i386: Make CMPXCHG64 only dependent on PAE

It is only used for PAE kernels in set_64bit.

The problem is that due to a old Windows bug many CPUs need magic MSRs
to enable CMPXCHG64, and we can't do that nicely early enough before
it is potentially used.

But since we only need it in PAE kernels so only force the checking
for CMPXCHG65 with PAE.

This fixes a boot failure on Transmeta Crusoe
Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

arch/i386/Kconfig

@@ -541,7 +541,7 @@ config HIGHMEM4G
 
 config HIGHMEM64G
 	bool "64GB"
-	depends on X86_CMPXCHG64
+	depends on !M386 && !M486
 	help
 	  Select this if you have a 32-bit processor and more than 4
 	  gigabytes of physical RAM.

arch/i386/Kconfig.cpu

@@ -299,7 +299,7 @@ config X86_POPAD_OK
 
 config X86_CMPXCHG64
 	bool
-	depends on !M386 && !M486
+	depends on X86_PAE
 	default y
 
 config X86_ALIGNMENT_16