rtc: RTC_DRV_SPEAR should not default to y when compile-testing

Merely enabling compile-testing should not enable additional
functionality.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Link: https://lore.kernel.org/r/7b8eefe3b0150101ba01c3ea55e45aa3134059ba.1733243007.git.geert+renesas@glider.be
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

drivers/rtc/Kconfig

@@ -1316,7 +1316,7 @@ config RTC_DRV_SC27XX
 config RTC_DRV_SPEAR
 	tristate "SPEAR ST RTC"
 	depends on PLAT_SPEAR || COMPILE_TEST
-	default y
+	default PLAT_SPEAR
 	help
 	 If you say Y here you will get support for the RTC found on
 	 spear