serial: 8250: SERIAL_8250_ASPEED_VUART should depend on ARCH_ASPEED

The Aspeed Virtual UART is only present on Aspeed BMC platforms.  Hence
add a dependency on ARCH_ASPEED, to prevent asking the user about this
driver when configuring a kernel without Aspeed BMC support.

Reviewed-by: Jeremy Kerr <jk@ozlabs.org>
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/r/259138c372d433005b4871789ef9ee8d15320307.1657528861.git.geert+renesas@glider.be


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>