watchdog: indydog: Add dependency on SGI_HAS_INDYDOG

Commit da2a68b3 ("watchdog: Enable COMPILE_TEST where possible")
enabled building the Indy watchdog driver when COMPILE_TEST is enabled.
However, the driver makes reference to symbols that are only defined for
certain platforms are selected in the config. These platforms select
SGI_HAS_INDYDOG. Without this, link time errors result, for example
when building a MIPS allyesconfig.

drivers/watchdog/indydog.o: In function `indydog_write':
indydog.c:(.text+0x18): undefined reference to `sgimc'
indydog.c:(.text+0x1c): undefined reference to `sgimc'
drivers/watchdog/indydog.o: In function `indydog_start':
indydog.c:(.text+0x54): undefined reference to `sgimc'
indydog.c:(.text+0x58): undefined reference to `sgimc'
drivers/watchdog/indydog.o: In function `indydog_stop':
indydog.c:(.text+0xa4): undefined reference to `sgimc'
drivers/watchdog/indydog.o:indydog.c:(.text+0xa8): more undefined
references to `sgimc' follow
make: *** [Makefile:1005: vmlinux] Error 1

Fix this by ensuring that CONFIG_INDIDOG can only be selected when the
necessary dependent platform symbols are built in.

Fixes: da2a68b3 ("watchdog: Enable COMPILE_TEST where possible")
Signed-off-by: Matt Redfearn <matt.redfearn@mips.com>
Cc: <stable@vger.kernel.org> # 4.11 +
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Suggested-by: James Hogan <james.hogan@mips.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>

drivers/watchdog/Kconfig

@@ -1451,7 +1451,7 @@ config RC32434_WDT
 
 config INDYDOG
 	tristate "Indy/I2 Hardware Watchdog"
-	depends on SGI_HAS_INDYDOG || (MIPS && COMPILE_TEST)
+	depends on SGI_HAS_INDYDOG
 	help
 	  Hardware driver for the Indy's/I2's watchdog. This is a
 	  watchdog timer that will reboot the machine after a 60 second