mmc: sdhci-omap: Remove setting ADMA capability in driver

sdhci can directly get ADMA capability from MMCHS_CAPA register.
Remove explicitly setting ADMA here as some instances might not have
ADMA enabled. (sdhci_read_caps() is also removed from here since
sdhci_setup_host() invokes it).

Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>
Acked-by: Adrian Hunter <adrian.hunter@intel.com>
Acked-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>