tty: serial: bcm63xx: lower driver dependencies

Hardware supported by bcm63xx is also used by BCM4908 SoCs family that
is ARM64. In future more architectures may need it as well. There is
nothing arch specific breaking compilation so just stick to requiring
COMMON_CLK.
Signed-off-by: Rafał Miłecki <rafal@milecki.pl>
Link: https://lore.kernel.org/r/20201125090608.28442-1-zajec5@gmail.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/serial/Kconfig

@@ -1117,7 +1117,7 @@ config SERIAL_TIMBERDALE
 config SERIAL_BCM63XX
 	tristate "Broadcom BCM63xx/BCM33xx UART support"
 	select SERIAL_CORE
-	depends on MIPS || ARM || COMPILE_TEST
+	depends on COMMON_CLK
 	help
 	  This enables the driver for the onchip UART core found on
 	  the following chipsets: