mmc: sdhci: Remove unneeded forward declaration of sdhci_finish_data()

sdhci_finish_data() is defined before it is referenced, so forward
declaration is not necessary.

Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Tested-by: Baolin Wang <baolin.wang7@gmail.com>
Link: https://lore.kernel.org/r/20200412090349.1607-4-adrian.hunter@intel.com


Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>