watchdog: intel_scu_watchdog: fix Kconfig dependency

Kernel symbol X86_MRST has been removed from the kernel.
INTEL_SCU_WATCHDOG driver can never be compiled due dependence of X86_MRST
which remained in the drivers/watchdog/Kconfig.

Reported-by: Alexander Shiyan <shc_work@mail.ru>
Cc: Alan Cox <alan@linux.intel.com>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>

drivers/watchdog/Kconfig

@@ -594,7 +594,7 @@ config IE6XX_WDT
 
 config INTEL_SCU_WATCHDOG
 	bool "Intel SCU Watchdog for Mobile Platforms"
-	depends on X86_MRST
+	depends on X86_INTEL_MID
 	---help---
 	  Hardware driver for the watchdog time built into the Intel SCU
 	  for Intel Mobile Platforms.