configs/raspberrypi: bump kernel version

Upstream has been playing evil-rebase on their tree, so they now
no longer have the changeset we are currently referencing.

They have now agreed to merge instead of rebasing:
    https://github.com/raspberrypi/linux/issues/584

So, update the raspberrypi_defconfig to use a new changeset that
currently exists right _now_, in the hope it will not disapear in
the future (but we'll catch it pretty fast anyway, so we'll be able
to seriously bug up upstream in that case ;-) ).

Reported-by: Jeremy Rosen <jeremy.rosen@openwide.fr>
Signed-off-by: yann.morin.1998@free.fr
Cc: Jeremy Rosen <jeremy.rosen@openwide.fr>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

configs/raspberrypi_defconfig

@@ -16,7 +16,7 @@ BR2_PACKAGE_HOST_LINUX_HEADERS_CUSTOM_3_12=y
 BR2_LINUX_KERNEL=y
 BR2_LINUX_KERNEL_CUSTOM_GIT=y
 BR2_LINUX_KERNEL_CUSTOM_REPO_URL="git://github.com/raspberrypi/linux.git"
-BR2_LINUX_KERNEL_CUSTOM_REPO_VERSION="746069c0ac473cfb4fd70415149b4cfdea193119"
+BR2_LINUX_KERNEL_CUSTOM_REPO_VERSION="81bd944c02f65f706ad257f113fd5b2f62cdd03f"
 BR2_LINUX_KERNEL_USE_DEFCONFIG=y
 BR2_LINUX_KERNEL_DEFCONFIG="bcmrpi_quick"
 BR2_LINUX_KERNEL_ZIMAGE=y