package/linux-headers: remove bogus symbol BR2_PACKAGE_HOST_LINUX_HEADERS

The package host-linux-headers does not exist and there were never
references to this symbol in the tree, do drop it.

Signed-off-by: Ricardo Martincoski <ricardo.martincoski@gmail.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>
(cherry picked from commit 367bd65f3c216426e2fc21742dbff11ea8d896d7)
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/linux-headers/Config.in.host

@@ -1,8 +1,5 @@
 comment "Kernel Header Options"
 
-config BR2_PACKAGE_HOST_LINUX_HEADERS
-	bool
-
 choice
 	prompt "Kernel Headers"
 	default BR2_KERNEL_HEADERS_AS_KERNEL if BR2_LINUX_KERNEL