mmc: eMMC partitioning data is not effective till partitioning completed

mmc: eMMC partitioning data is not effective till partitioning completed

The eMMC spec says that partitioning is only effective after the
PARTITION_SETTING_COMPLETED is set in EXT_CSD (and a power cycle was done,
but that we cannot know). Thus the partition sizes and attributes should
be ignored when that bit is not set, otherwise the various capacities
are not coherent (e.g., the user data capacity will be that of the
unpartitioned device while partition sizes would be non-zero).

Prescence of non-zero partitioning data is nevertheless still used to
activate the high-capacity size definitions (EXT_CSD_ERASE_GROUP_DEF)
as it is necessary to set that to write any of the partitioning fields
in EXT_CSD, so having partitioning data means someone previously
activated that and we should keep it activated.

Signed-off-by: Diego Santa Cruz <Diego.SantaCruz@spinetix.com>