kernel: bump 4.14 to 4.14.20

Refresh patches.
Remove upstreamed patches:
- backport/080-v4.15-0001-arch-define-weak-abort.patch
- backport/081-v4.15-0002-kernel-exit.c-export-abort-to-modules.patch
Update patch that no longer applies:
pending/493-ubi-set-ROOT_DEV-to-ubiblock-rootfs-if-unset.patch

Fixes CVE-2017-8824.

Compile-tested: octeon, x86/64.
Runtime-tested: octeon, x86/64.

Signed-off-by: Stijn Tintel <stijn@linux-ipv6.be>

target/linux/generic/hack-4.14/207-disable-modorder.patch

@@ -15,7 +15,7 @@ Signed-off-by: Felix Fietkau <nbd@nbd.name>
 
 --- a/Makefile
 +++ b/Makefile
-@@ -1212,7 +1212,6 @@ all: modules
+@@ -1213,7 +1213,6 @@ all: modules
  
  PHONY += modules
  modules: $(vmlinux-dirs) $(if $(KBUILD_BUILTIN),vmlinux) modules.builtin
@@ -23,7 +23,7 @@ Signed-off-by: Felix Fietkau <nbd@nbd.name>
  	@$(kecho) '  Building modules, stage 2.';
  	$(Q)$(MAKE) -f $(srctree)/scripts/Makefile.modpost
  
-@@ -1241,7 +1240,6 @@ _modinst_:
+@@ -1242,7 +1241,6 @@ _modinst_:
  		rm -f $(MODLIB)/build ; \
  		ln -s $(CURDIR) $(MODLIB)/build ; \
  	fi