ZEN: Tune default CLEAN_LOW/MIN_KBYTES values

Use safe default values so the le9 patch set.  Systems with more memory
will may want a more aggressive tune.

Signed-off-by: kernelOfTruth <kerneloftruth@gmail.com>

mm/Kconfig

@@ -124,7 +124,7 @@ config SPARSEMEM_VMEMMAP
 config CLEAN_LOW_KBYTES
 	int "Default value for vm.clean_low_kbytes"
 	depends on SYSCTL
-	default "0"
+	default "262144"
 	help
 	  The vm.clean_low_kbytes sysctl knob provides *best-effort*
 	  protection of clean file pages. The clean file pages on the current
@@ -142,7 +142,7 @@ config CLEAN_LOW_KBYTES
 config CLEAN_MIN_KBYTES
 	int "Default value for vm.clean_min_kbytes"
 	depends on SYSCTL
-	default "0"
+	default "65536"
 	help
 	  The vm.clean_min_kbytes sysctl knob provides *hard* protection
 	  of clean file pages. The clean file pages on the current node won't be