package/libss7: add Linux in comment

Add "Linux" before kernel in comment to be consistent with other
packages and manual

Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Signed-off-by: Yann E. MORIN <yann.morin.1998@free.fr>
(cherry picked from commit e0de6291e3fe8d9f6c572a5206b8ead3719f6829)
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/libss7/Config.in

@@ -12,7 +12,7 @@ config BR2_PACKAGE_LIBSS7
 
 	  http://www.asterisk.org/downloads/libss7
 
-comment "libss7 needs a kernel to be built"
+comment "libss7 needs a Linux kernel to be built"
 	depends on !BR2_LINUX_KERNEL
 
 comment "libss7 needs a toolchain w/ threads"