kernel: add missing symbol for v4.14

Signed-off-by: John Crispin <[email protected]>

target/linux/generic/config-4.14

@@ -590,6 +590,7 @@ CONFIG_BOOKE_WDT_DEFAULT_TIMEOUT=3
 CONFIG_BOOT_RAW=y
 CONFIG_BPF=y
 # CONFIG_BPF_JIT is not set
+# CONFIG_BPF_JIT_ALWAYS_ON is not set
 # CONFIG_BPF_STREAM_PARSER is not set
 CONFIG_BPF_SYSCALL=y
 # CONFIG_BPQETHER is not set