qemu/mips64-malta: update to use kernel 3.6.6

Signed-off-by: Gustavo Zacarias <gustavo@zacarias.com.ar>
Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>

board/qemu/mips64-malta/readme.txt

@@ -5,3 +5,7 @@ Run the emulation with:
 The login prompt will appear in the terminal that started Qemu. The
 graphical window is the framebuffer. No keyboard support has been
 enabled.
+
+This configuration is known to be flaky.
+
+Tested with QEMU 1.2.0

configs/qemu_mips64_malta_defconfig

@@ -10,12 +10,15 @@ BR2_PREFER_STATIC_LIB=y
 BR2_TARGET_ROOTFS_EXT2=y
 # BR2_TARGET_ROOTFS_TAR is not set
 
+# Lock to 3.6 headers to avoid breaking with newer kernels
+BR2_KERNEL_HEADERS_3_6=y
+
 # Kernel
 BR2_LINUX_KERNEL=y
 BR2_LINUX_KERNEL_CUSTOM_VERSION=y
-BR2_LINUX_KERNEL_CUSTOM_VERSION_VALUE="3.5.4"
+BR2_LINUX_KERNEL_CUSTOM_VERSION_VALUE="3.6.6"
 BR2_LINUX_KERNEL_USE_CUSTOM_CONFIG=y
-BR2_LINUX_KERNEL_CUSTOM_CONFIG_FILE="board/qemu/mips64-malta/linux-3.5.config"
+BR2_LINUX_KERNEL_CUSTOM_CONFIG_FILE="board/qemu/mips64-malta/linux-3.6.config"
 BR2_LINUX_KERNEL_VMLINUX=y
 
 # Serial port config