mmc: sdhci-of-at91: fix MMC_DDR_52 timing selection

commit d0918764c17b94c30bbb2619929b1719ff52707a upstream.

The controller has different timings for MMC_TIMING_UHS_DDR50 and
MMC_TIMING_MMC_DDR52. Configuring the controller with SDHCI_CTRL_UHS_DDR50,
when MMC_TIMING_MMC_DDR52 timings are requested, is not correct and can
lead to unexpected behavior.

Signed-off-by: Ludovic Desroches <ludovic.desroches@microchip.com>
Fixes: bb5f8ea4 ("mmc: sdhci-of-at91: introduce driver for the Atmel SDMMC")
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>