EmbeddedPkg/MmcDxe: Add non-DDR timing mode support
EmbeddedPkg/MmcDxe: Add non-DDR timing mode support

Only DDR mode is support for 8bit mode currently. Add
non-DDR case when configuring ECSD.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Jun Nie <16d8bc3f29c489fdc436b48884adedee8c6f9a7b@linaro.org>
Reviewed-by: Leif Lindholm <a613079f0455438b29e28a9c5b9eb3779a81a33a@linaro.org>

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