linux: remove default for custom kernel version

There already is a default kernel version, so it makes little sense to have
a default custom kernel version as well.  This default breaks the 'make
savedefconfig' if we want to force a specific version.

Signed-off-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>
Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>

linux/Config.in

@@ -58,7 +58,6 @@ endchoice
 config BR2_LINUX_KERNEL_CUSTOM_VERSION_VALUE
 	string "Kernel version"
 	depends on BR2_LINUX_KERNEL_CUSTOM_VERSION
-	default "3.2.1"
 
 config BR2_LINUX_KERNEL_CUSTOM_TARBALL_LOCATION
 	string "URL of custom kernel tarball"