mmc: usdhi6rol0: Fix a resource leak in the error handling path of the probe

mmc: usdhi6rol0: Fix a resource leak in the error handling path of the probe

A call to 'ausdhi6_dma_release()' to undo a previous call to
'usdhi6_dma_request()' is missing in the error handling path of the probe
function.

It is already present in the remove function.

Fixes: 75fa9ea6e3c0 ("mmc: add a driver for the Renesas usdhi6rol0 SD/SDIO host controller")
Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Link: https://lore.kernel.org/r/20201217210922.165340-1-christophe.jaillet@wanadoo.fr
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>