linux: Add stable version 4.7.2

Do as Greg says [1]:

> All users of the 4.7 kernel series must upgrade.

Summary of changes [2]:

> ### Here's what's new in Linux kernel 4.7.2 ###
>
> As mentioned before, the changes are big, and they include numerous
> improvements to the ARM64 (AArch64), ARM, ARC, MIPS, s390, x86, and
> PowerPC (PPC), as well as multiple updated drivers, in particular for
> AMDGPU, ACPI, BCMA, Bluetooth, GPIO, CLK, CPUFreq, EDAC, Intel i915,
> Nouveau, Radeon, Rockchip, I2C, InfiniBand, IOMMU, MD, MFD, iwlwifi,
> PHY, PINCTRL, SCSI, SPI, TTY, USB, and Virtio.
>
> Additionally, Linux kernel 4.7.2 comes with improved filesystem
> support, which includes changes for Btrfs, CIFS, JBD2, NFS, OverlayFS,
> and XFS.  Lastly, some core kernel, mm, core networking, and sound
> stack enhancements are also present. Linux kernel 4.7.2 is available
> for download right now via our website or directly from kernel.org, so
> please update as soon as possible.

[1] https://lkml.org/lkml/2016/8/20/61
[2] http://news.softpedia.com/news/linux-kernel-4-7-2-is-a-big-update-with-numerous-amdgpu-and-arm64-improvements-507504.shtml