serial: 8250_lpss: make option visible

Hiding tristate options with "if EXPERT" is usually not a good idea.
You can decide that the driver should be included by default, but you
don't know if the user wants it built-in or as a module. Hiding the
option prevents the user from making that decision.

This is even more problematic when said option selects other options.
You end up with several device drivers forcibly built into the kernel.

In this specific case, drivers 8250_lpss, dw_dmac_core and
dw_dmac_pci end up being built-in as soon as SERIAL_8250=y. It is
very common for distribution kernels to build the subsystem core code
into the kernel, because almost everybody will need it, but build all
the device drivers as modules. This should be made possible.

So drop the "if EXPERT" and make SERIAL_8250_LPSS visible.

Signed-off-by: Jean Delvare <jdelvare@suse.de>
Fixes: a13e19cf ("serial: 8250_lpss: split LPSS driver to separate module")
Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Jiri Slaby <jslaby@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>