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/mediatek/patches-4.14/0046-net-mediatek-add-irq-delay.patch

@@ -9,10 +9,8 @@ Signed-off-by: John Crispin <john@phrozen.org>
  drivers/net/ethernet/mediatek/mtk_eth_soc.h | 8 +++++++-
  2 files changed, 13 insertions(+), 2 deletions(-)
 
-Index: linux-4.14.11/drivers/net/ethernet/mediatek/mtk_eth_soc.c
-===================================================================
---- linux-4.14.11.orig/drivers/net/ethernet/mediatek/mtk_eth_soc.c
-+++ linux-4.14.11/drivers/net/ethernet/mediatek/mtk_eth_soc.c
+--- a/drivers/net/ethernet/mediatek/mtk_eth_soc.c
++++ b/drivers/net/ethernet/mediatek/mtk_eth_soc.c
 @@ -1994,6 +1994,7 @@ static int mtk_hw_init(struct mtk_eth *e
  
  	/* enable interrupt delay for RX */