diag: Flush mdlog table entries while reallocation of data buffer

Currently there is a possibility of accessing freed up buffer
address after reallocation due to availability of old address
in mdlog entry table. The patch flushes table entries before
reallocating data buffer. Additional case of entries cleanup
during erroneous buffer free and wrong length update for
user PD buffer avoiding further buffer corruption.

CRs-Fixed: 2063721
Change-Id: I8424598ad34b809414518a1f7f5b1737ebe51e53
Signed-off-by: Hardik Arya <harya@codeaurora.org>