mmc: omap_hsmmc: don't print uninitialized variables

When DT based probing is used but the DMA request fails, the
driver will print uninitialized stack data from the rx_req
and tx_req variables, as indicated by this warning:

drivers/mmc/host/omap_hsmmc.c: In function 'omap_hsmmc_probe':
drivers/mmc/host/omap_hsmmc.c:2162:3: warning: 'rx_req' may be used uninitialized in this function [-Wmaybe-uninitialized]
   dev_err(mmc_dev(host->mmc), "unable to obtain RX DMA engine channel %u\n", rx_req);

This removes the DMA request line number from the warning, which
is the easiest solution and won't hurt us any more as we are
planning to remove the legacy code path anyway.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Tony Lindgren <tony@atomide.com>
Reviewed-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>