Config.in: bump default JLEVEL to 2

With multicores everywhere, 2 is probably a bit low - But atleast it's
better than the current default.

This extra parallelism also ensures we get to test the make dependencies
a bit more.

Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>

Config.in

@@ -132,7 +132,7 @@ config BR2_GNU_TARGET_SUFFIX
 
 config BR2_JLEVEL
 	int "Number of jobs to run simultaneously"
-	default "1"
+	default "2"
 	help
 	  Number of jobs to run simultaneously