ASoC: msm: qdsp6v2: Correct buffer address data type

While retrieving the memory map handles from the list,
the buffer physical address is getting truncated by
errorneous type-casting from 64-bit to 32-bit. Because
of this memory map handle corresponding to that physical
address will not get retrieved from the list and hence
it never gets unmapped.

CRs-Fixed: 813971
Change-Id: I2914c8556286ba9106aad625e5878afb6bb56b09
Signed-off-by: Phani Kumar Uppalapati <phaniu@codeaurora.org>