kernel: mark kmod-thermal menuconfig symbol as hidden to avoid building it on targets with no thermal drivers

Should fix build errors with Linux 3.3/3.6 targets, which use different
kconfig symbols

Signed-off-by: Felix Fietkau <nbd@openwrt.org>

SVN-Revision: 38238

package/kernel/linux/modules/other.mk

@@ -765,6 +765,7 @@ $(eval $(call KernelPackage,random-core))
 define KernelPackage/thermal
   SUBMENU:=$(OTHER_MENU)
   TITLE:=Generic Thermal sysfs driver
+  HIDDEN:=1
   KCONFIG:= \
 	CONFIG_THERMAL \
 	CONFIG_THERMAL_DEFAULT_GOV_STEP_WISE=y \