mmc: Implement SD/MMC versioning properly

The SD/MMC version scheme was buggy when dealing with standard
major.minor.change cases. Fix it by using something similar to
the linux's kernel versioning method.

Signed-off-by: Pantelis Antoniou <pantelis.antoniou@konsulko.com>
Tested-by: Jaehoon Chung <jh80.chung@samsung.com>
Reported-by: Stephen Warren <swarren@nvidia.com>
Tested-by: Stephen Warren <swarren@nvidia.com>