qemu/mips64-malta: update defconfig to Linux 3.15.x

Update default to 3.15.x.

Signed-off-by: Waldemar Brodkorb <wbx@openadk.org>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

board/qemu/mips64-malta/readme.txt

@@ -5,4 +5,4 @@ Run the emulation with:
 The login prompt will appear in the terminal that started Qemu. The
 graphical window is the framebuffer.
 
-Tested with QEMU 1.7.0
+Tested with QEMU 2.0.0

configs/qemu_mips64_malta_defconfig

@@ -6,17 +6,17 @@ BR2_MIPS_NABI64=y
 BR2_TARGET_ROOTFS_EXT2=y
 # BR2_TARGET_ROOTFS_TAR is not set
 
-# Lock to 3.13 headers to avoid breaking with newer kernels
+# Lock to 3.15 headers to avoid breaking with newer kernels
 BR2_KERNEL_HEADERS_VERSION=y
-BR2_DEFAULT_KERNEL_VERSION="3.13.5"
-BR2_PACKAGE_HOST_LINUX_HEADERS_CUSTOM_3_13=y
+BR2_DEFAULT_KERNEL_VERSION="3.15.6"
+BR2_PACKAGE_HOST_LINUX_HEADERS_CUSTOM_3_15=y
 
 # Kernel
 BR2_LINUX_KERNEL=y
 BR2_LINUX_KERNEL_CUSTOM_VERSION=y
-BR2_LINUX_KERNEL_CUSTOM_VERSION_VALUE="3.13.5"
+BR2_LINUX_KERNEL_CUSTOM_VERSION_VALUE="3.15.6"
 BR2_LINUX_KERNEL_USE_CUSTOM_CONFIG=y
-BR2_LINUX_KERNEL_CUSTOM_CONFIG_FILE="board/qemu/mips64-malta/linux-3.13.config"
+BR2_LINUX_KERNEL_CUSTOM_CONFIG_FILE="board/qemu/mips64-malta/linux-3.15.config"
 BR2_LINUX_KERNEL_VMLINUX=y
 
 # Serial port config