serial: lantiq: Add x86 in Kconfig dependencies for Lantiq serial driver

Lantiq serial driver/IP is reused for a x86 based SoC as well.
Update the Kconfig accordingly.
Signed-off-by: Rahul Tanwar <rahul.tanwar@linux.intel.com>
Link: https://lore.kernel.org/r/96fd193c0a8939d27641ff93573545c02313048f.1588577002.git.rahul.tanwar@linux.intel.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/serial/Kconfig

@@ -1035,7 +1035,7 @@ config SERIAL_SIFIVE_CONSOLE
 
 config SERIAL_LANTIQ
 	bool "Lantiq serial driver"
-	depends on LANTIQ
+	depends on (LANTIQ || X86) || COMPILE_TEST
 	select SERIAL_CORE
 	select SERIAL_CORE_CONSOLE
 	select SERIAL_EARLYCON