mmc: make mmc_set_ios() return status

set_ios callback has a return value of 'int' but the mmc_set_ios()
function ignore this. Modify mmc_set_ios() and the callers of mmc_set_ios() to
to return the error status.

Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>
Signed-off-by: Jean-Jacques Hiblot <jjhiblot@ti.com>
Reviewed-by: Simon Glass <sjg@chromium.org>