x86: Update kernel for alix2 to 3.10.15

Without this patch, the patch
target/linux/generic/patches-3.10/770-bgmac-backport.patch
would not apply.

Signed-off-by: Tobias Steinicke <tsteinicke@net.t-labs.tu-berlin.de>

SVN-Revision: 38438

target/linux/x86/alix2/target.mk

@@ -19,7 +19,7 @@ DEFAULT_PACKAGES += \
 			kmod-ledtrig-heartbeat kmod-ledtrig-gpio \
 			kmod-ledtrig-netdev \
 			kmod-cpu-msr hwclock wpad
-LINUX_VERSION:=3.10.13
+LINUX_VERSION:=3.10.15
 CS5535_MASK:=0x0b000042
 
 CPU_TYPE := geode