kernel: update kernel 4.4 to version 4.4.15

include/kernel-version.mk

...hy-bcm-ns-usb2-new-driver-for-USB-2.0-PHY-on-Norths.patch

...89-0002-phy-bcm-ns-usb2-checking-the-wrong-variable.patch

...190-usb-xhci-plat-fix-adding-usb3-lpm-capable-quirk.patch

...pf-add-skb_postpush_rcsum-and-fix-dev_forward_skb-o.patch

target/linux/brcm47xx/patches-4.4/999-wl_exports.patch

target/linux/brcm63xx/patches-4.4/800-wl_exports.patch

...RC-unwind-ensure-that-.debug_frame-is-generated-vs..patch

...generic/patches-4.4/645-bridge_multicast_to_unicast.patch

..._fix_ipv6_mc_snooping_if_bridge_has_no_ipv6_address.patch

...4.4/821-usb-Remove-annoying-warning-about-bogus-URB.patch

...-net-igb-register-mii_bus-for-SerDes-w-external-phy.patch

...0019-xhci-mediatek-support-MTK-xHCI-host-controller.patch

...0033-xhci-mediatek-support-MTK-xHCI-host-controller.patch

target/linux/ramips/patches-4.4/0085-pinmux-util.patch

target/linux/ramips/patches-4.4/0085-sdhci-no-wp.patch

...t/linux/ramips/patches-4.4/0105-set_mt7621_soc_type.patch

target/linux/ramips/patches-4.4/0519-gsw_mt7621.patch

target/linux/ramips/patches-4.4/0520-esw-gmac.patch

...ps/patches-4.4/0720-arch-mips-ralink-add-i2c-clocks.patch