tmio_mmc: Fix use after free in remove()

Update the tmio_mmc code to call mmc_free_host() when
done using the private data. Without this fix the driver
frees memory and then keeps on using it as private data.

Signed-off-by: Magnus Damm <damm@opensource.se>
Acked-by: Ian Molton <ian@mnementh.co.uk>
Signed-off-by: Pierre Ossman <drzeus@drzeus.cx>