[PATCH RESEND v7 0/3] mmc: core: Support packed command feature of eMMC4.5

This patch-set adds support of packed command feature
for eMMC4.5 devices.

This is resending of v7 because review of Subhash Jadavani in v6 is not applied properly.

Changes in v7:
	- Break the endless execution in some error handling(from Maya Erez).
	- Change the condition for enabling packed command(from Subhash Jadavani).
	- Spilt the error related routine from mmc_blk_issue_rw_rq.

Changes in v6:
	- Split the patch for packed read.
	- Remove the unnecessary code. 

Changes in v5:
	- Revert "Add a variable member in mmc_host for minimum number of packed entries".
	- Fix the partial packed command from failure index.
	- Clean an unnecessary parameter of mmc_blk_packed_hdr_wrq_prep 
	- Clean warning of checkpatch.

Changes in v4:
	- Add Data-tag as CMD23 argument for packed header.
	- Separate the capability of MMC_CAP2_PACKED_CMD into read and write.
	- Remove unncessary initial value.

Changes in v3:
	- Add a variable member in mmc_host for minimum number of packed entries.
	  This value can be overridden by host.
	- Fix a handling of error sequence.