mmc: sdhci: factor out common DMA cleanup in sdhci_finish_data()

sdhci_finish_data() has two paths which result in identical DMA cleanup.
One is when SDHCI_USE_ADMA is clear, and the other is just before when
SDHCI_USE_ADMA is set, and is performed within sdhci_adma_table_post().

Simplify the code by removing the 'else' and eliminating the duplicate
inside sdhci_adma_table_post().

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Tested-by: Gregory CLEMENT <gregory.clement@free-electrons.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>