ata: ahci_st: Enable compile test

Enable compiling the ahci_st driver when COMPILE_TEST is enabled.

Signed-off-by: Damien Le Moal <damien.lemoal@opensource.wdc.com>
diff --git a/drivers/ata/Kconfig b/drivers/ata/Kconfig
index 1a8a1bb..36833a8 100644
--- a/drivers/ata/Kconfig
+++ b/drivers/ata/Kconfig
@@ -188,7 +188,7 @@
 
 config AHCI_ST
 	tristate "ST AHCI SATA support"
-	depends on ARCH_STI
+	depends on ARCH_STI || COMPILE_TEST
 	select SATA_HOST
 	help
 	  This option enables support for ST AHCI SATA controller.