[media] siano: break it into common, mmc and usb

siano is, in fact, 2 drivers: one for MMC and one for USB, plus
a common bus-independent code. Break it accordingly.

Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
diff --git a/drivers/media/mmc/Kconfig b/drivers/media/mmc/Kconfig
new file mode 100644
index 0000000..0f2a957
--- /dev/null
+++ b/drivers/media/mmc/Kconfig
@@ -0,0 +1 @@
+source "drivers/media/mmc/siano/Kconfig"