cnss: Reserve 0-4K memory for QCA6174

MAC hardware on QCA6174 has a bug that is causing an invalid pointer
fetch based on the data that is read from 0 to 4K. And when the
data read from 0 to 4K address range is translating to a high
order address, PCIe RC would return a read abort error, and that
results in an internal AXI error. So allocate/reserve this memory
and fill it with zero's (populate the redirected 0 to 4K to a memory
address that is essentially populated with data that translates
to an address for which PCIe RC honored the read without any errors).
Note that the read value is not used by MAC for any further
operations.

CRs-Fixed: 658944
Change-Id: Ic53ef99e20651d3f5e5649ab25a1599eba0f09c2
Signed-off-by: Sameer Thalappil <sameert@codeaurora.org>