ata: Kconfig: fix sata gemini compile test condition

When compile testing the sata gemini driver, CONFIG_OF is required to
avoid the warning:

drivers/ata/sata_gemini.c:421:34: error: ‘gemini_sata_of_match’ defined
but not used [-Werror=unused-const-variable=]
Signed-off-by: NDamien Le Moal <damien.lemoal@opensource.wdc.com>

drivers/ata/Kconfig

@@ -283,7 +283,7 @@ config SATA_FSL
 
 config SATA_GEMINI
 	tristate "Gemini SATA bridge support"
-	depends on ARCH_GEMINI || COMPILE_TEST
+	depends on ARCH_GEMINI || (OF && COMPILE_TEST)
 	select SATA_HOST
 	default ARCH_GEMINI
 	help