bcm53xx: switch to kernel 4.9

With iproc regression fixed and GIC interrupts in DTS updated it seems
we can safely start using 4.9.

Signed-off-by: Rafał Miłecki <[email protected]>

target/linux/bcm53xx/Makefile

@@ -13,7 +13,7 @@ FEATURES:=squashfs nand usb pci pcie gpio
 MAINTAINER:=Hauke Mehrtens <[email protected]>
 CPU_TYPE:=cortex-a9
 
-KERNEL_PATCHVER:=4.4
+KERNEL_PATCHVER:=4.9
 
 define Target/Description
 	Build firmware images for Broadcom based BCM47xx/53xx routers with ARM CPU, *not* MIPS.