tmio_mmc: Fix one off, use resource_size() in probe()

Update the tmio_mmc code to use resource_size(). With this
patch applied the correct resource size is passed to ioremap().

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