kernel: bump 4.9 to 4.9.116

Refreshed all patches

Remove upstreamed patches.
- 103-MIPS-ath79-fix-register-address-in-ath79_ddr_wb_flus.patch
- 403-mtd_fix_cfi_cmdset_0002_status_check.patch
- 001-4.11-01-mtd-m25p80-consider-max-message-size-in-m25p80_read.patch
- 001-4.15-08-bcm63xx_enet-correct-clock-usage.patch
- 001-4.15-09-bcm63xx_enet-do-not-write-to-random-DMA-channel-on-B.patch
- 900-gen_stats-fix-netlink-stats-padding.patch

Introduce a new backported patch to address ext4 breakage, introduced in 4.9.112
- backport-4.9/500-ext4-fix-check-to-prevent-initializing-reserved-inod.patch

This patch has been slightly altered to compensate for a new helper function
introduced in later kernels.

Also add ARM64_SSBD symbol to ARM64 targets still running kernel 4.9

Compile-tested on: ar71xx, bcm2710
Runtime-tested on: ar71xx

Signed-off-by: Koen Vandeputte <koen.vandeputte@ncentric.com>

target/linux/generic/pending-4.9/201-extra_optimization.patch

@@ -14,7 +14,7 @@ Signed-off-by: Felix Fietkau <nbd@nbd.name>
 
 --- a/Makefile
 +++ b/Makefile
-@@ -642,12 +642,12 @@ KBUILD_CFLAGS	+= $(call cc-option,-fdata
+@@ -643,12 +643,12 @@ KBUILD_CFLAGS	+= $(call cc-option,-fdata
  endif
  
  ifdef CONFIG_CC_OPTIMIZE_FOR_SIZE