toolchain/kernel-headers: not just 2.6 for manual version

The manual linux headers option may specify versions other than the 2.6
series, so drop the "2.6"

Signed-off-by: Gustavo Zacarias <gustavo@zacarias.com.ar>
Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>

toolchain/kernel-headers/Config.in

@@ -43,7 +43,7 @@ choice
 		bool "Linux 3.7.x kernel headers"
 
 	config BR2_KERNEL_HEADERS_VERSION
-		bool "Linux 2.6 (manually specified version)"
+		bool "Manually specified Linux version"
 
 	config BR2_KERNEL_HEADERS_SNAP
 		bool "Local Linux snapshot (linux-2.6.tar.bz2)"