spi_qsd: support to transfer 64K chunks in DM mode

Support to transfer 64K bytes in a single SPI
transfer in DMA mode on targets which support
16 bits in QUP_MX_OUTPUT_CNT register. Earlier
if the application sends more than 4K data it is
split up in to 4K chunks,  irrespective of the size
of the QUP_MX_OUTPUT_CNT register.

CRs-Fixed: 383120
Signed-off-by: Kiran Gunda <kgunda@codeaurora.org>
(cherry picked from commit c5fbd7f2)

Change-Id: Idb27c651e0a81a4efe363feabc44e26c5b61fb0f
Signed-off-by: Sudhir Sharma <sudsha@codeaurora.org>