platform: msm_shared: Flush the cache only for size of data
platform: msm_shared: Flush the cache only for size of data

Emmc reads can happen for sizes less than 512 Bytes, after enabling
write back caches we need to make sure that we flush the exact size
of data after read operation is performed.

Change-Id: I8e6b664b23811157b5f9ff431a68b9254635b021

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