Release 4.4.77-openpower1

Update to the latest stable release. This pulls in some backports for
NVMe stability.

The "drivers/drm/ast: Switch SCU to VGA output on POST" patch was
forward ported so it applied.

Signed-off-by: Joel Stanley <joel@jms.id.au>
diff --git a/openpower/configs/openpower_mambo_defconfig b/openpower/configs/openpower_mambo_defconfig
index a1d1ddc..86901c7 100644
--- a/openpower/configs/openpower_mambo_defconfig
+++ b/openpower/configs/openpower_mambo_defconfig
@@ -31,7 +31,7 @@
 BR2_ROOTFS_POST_BUILD_SCRIPT="../openpower/scripts/fixup-target-var"
 BR2_LINUX_KERNEL=y
 BR2_LINUX_KERNEL_CUSTOM_VERSION=y
-BR2_LINUX_KERNEL_CUSTOM_VERSION_VALUE="4.4.70"
+BR2_LINUX_KERNEL_CUSTOM_VERSION_VALUE="4.4.77"
 BR2_KERNEL_HEADERS_4_4=y
 BR2_BINUTILS_VERSION_2_26_X=y
 BR2_LINUX_KERNEL_PATCH="$(BR2_EXTERNAL)/linux"