toolchain-external: on ARM, show comment about the availability of Linaro toolchains

On ARM, Linaro external toolchains are only visible if the user
selects Cortex-A8 or Cortex-A9. Therefore, we add a comment that tells
the user that the Linaro toolchains are only available under those
conditions.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>

toolchain/toolchain-external/Config.in

@@ -54,6 +54,10 @@ config BR2_TOOLCHAIN_EXTERNAL_LINARO_2012_09
 
 	  To use this toolchain, you must disable soft float usage.
 
+comment "Linaro toolchains available for Cortex-A{8,9}"
+	depends on BR2_arm
+	depends on !BR2_cortex_a8 && !BR2_cortex_a9
+
 config BR2_TOOLCHAIN_EXTERNAL_CODESOURCERY_ARM201203
 	bool "Sourcery CodeBench ARM 2012.03"
 	depends on BR2_arm