Remove kernel-headers 6.8 option (legacy)

Author: rtissera

package/linux-headers/Config.in.host

@@ -48,10 +48,6 @@ config BR2_KERNEL_HEADERS_6_6
 	bool "Linux 6.6.x kernel headers"
 	select BR2_TOOLCHAIN_HEADERS_AT_LEAST_6_6
 
-config BR2_KERNEL_HEADERS_6_8
-	bool "Linux 6.8.x kernel headers"
-	select BR2_TOOLCHAIN_HEADERS_AT_LEAST_6_8
-
 config BR2_KERNEL_HEADERS_6_12
 	bool "Linux 6.12.x kernel headers"
 	select BR2_TOOLCHAIN_HEADERS_AT_LEAST_6_12