hw/i386/Kconfig: ISAPC works fine without VGA_ISA

The "isapc" machine can also be run without VGA card, so there
is no need for a hard requirement with a "select" here - "imply"
is enough.

Message-Id: <20230512124033.502654-2-thuth@redhat.com>
Acked-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>

hw/i386/Kconfig

@@ -80,10 +80,10 @@ config I440FX
 
 config ISAPC
     bool
+    imply VGA_ISA
     select ISA_BUS
     select PC
     select IDE_ISA
-    select VGA_ISA
     # FIXME: it is in the same file as i440fx, and does not compile
     # if separated
     depends on I440FX