brcm2708: disable CONFIG_BCM2835_THERMAL by default

This fixes:
  Thermal sensors on bcm2835 SoC (BCM2835_THERMAL) [N/m/y/?] (NEW) aborted!

This symbol depends on ARCH_BCM2835 so it should be OK to disable it at
brcm2708 target only.

Fixes: 7d32caa61fb0 ("brcm2708: backport upstream sdhost controller driver")
Signed-off-by: Rafał Miłecki <rafal@milecki.pl>

target/linux/brcm2708/bcm2708/config-4.9

@@ -45,6 +45,7 @@ CONFIG_BCM2708_VCMEM=y
 CONFIG_BCM2835_FAST_MEMCPY=y
 CONFIG_BCM2835_MBOX=y
 # CONFIG_BCM2835_SMI is not set
+# CONFIG_BCM2835_THERMAL is not set
 CONFIG_BCM2835_TIMER=y
 CONFIG_BCM2835_WDT=y
 CONFIG_BCM_VCIO=y

target/linux/brcm2708/bcm2709/config-4.9

@@ -52,6 +52,7 @@ CONFIG_BCM2708_VCMEM=y
 # CONFIG_BCM2835_DEVGPIOMEM is not set
 CONFIG_BCM2835_MBOX=y
 # CONFIG_BCM2835_SMI is not set
+# CONFIG_BCM2835_THERMAL is not set
 CONFIG_BCM2835_TIMER=y
 CONFIG_BCM2835_WDT=y
 CONFIG_BCM_VCIO=y

target/linux/brcm2708/bcm2710/config-4.9

@@ -71,6 +71,7 @@ CONFIG_BCM2708_VCMEM=y
 # CONFIG_BCM2835_DEVGPIOMEM is not set
 CONFIG_BCM2835_MBOX=y
 # CONFIG_BCM2835_SMI is not set
+# CONFIG_BCM2835_THERMAL is not set
 CONFIG_BCM2835_WDT=y
 # CONFIG_BCM_PDC_MBOX is not set
 # CONFIG_BCM_VCIO is not set