mmc: block: Add MMC write packing statistics

The write packing statistics are used for the packed commands unit tests
in order to determine test success or failure

Change-Id: I5eea513991c794543fbb3d009d8b7db0b0912fc5
Signed-off-by: Maya Erez <merez@codeaurora.org>
Signed-off-by: Tatyana Brokhman <tlinder@codeaurora.org>
5 files changed