superio/nuvoton/nct6776: Make Kconfig symbol dependent

The SUPERIO_NUVOTON_NCT6776_COM_A symbol should only be visible if
SUPERIO_NUVOTON_NCT6776 is selected as well.

Change-Id: I9c52d596080360bf3fc25265749ced66ec44f5dc
Signed-off-by: Angel Pons <th3fanbus@gmail.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/33440
Reviewed-by: Felix Held <felix-coreboot@felixheld.de>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
diff --git a/src/superio/nuvoton/nct6776/Kconfig b/src/superio/nuvoton/nct6776/Kconfig
index 90d4d32..441692b 100644
--- a/src/superio/nuvoton/nct6776/Kconfig
+++ b/src/superio/nuvoton/nct6776/Kconfig
@@ -20,4 +20,5 @@
 
 config SUPERIO_NUVOTON_NCT6776_COM_A
 	bool
+	depends on SUPERIO_NUVOTON_NCT6776
 	default n