hw/i386/Kconfig: Allow to compile Q35 without FDC_ISA

hw/i386/Kconfig: Allow to compile Q35 without FDC_ISA

The q35 machine can be used without floppy disk controller (FDC),
but due to our current Kconfig setup, the FDC code is still always
included in the binary. To fix this, the "PC" config option should
only imply the "FDC_ISA" instead of always selecting it.

The i440fx and the isa-pc machine currently always instantiate
the FDC, so we have to add the select statements now there instead.

Signed-off-by: Thomas Huth <thuth@redhat.com>
Acked-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Message-ID: <20240425184315.553329-3-thuth@redhat.com>
Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>