dmaengine: qcom_hidma: initialize tx flags in hidma_prep_dma_*

In async_tx_test_ack(), it uses flags in struct dma_async_tx_descriptor
to check the ACK status. As hidma reuses the descriptor in a free list
when hidma_prep_dma_*(memcpy/memset) is called, the flag will keep ACKed
if the descriptor has been used before. This will cause a BUG_ON in
async_tx_quiesce().

  kernel BUG at crypto/async_tx/async_tx.c:282!
  Internal error: Oops - BUG: 0 1 SMP
  ...
  task: ffff8017dd3ec000 task.stack: ffff8017dd3e8000
  PC is at async_tx_quiesce+0x54/0x78 [async_tx]
  LR is at async_trigger_callback+0x98/0x110 [async_tx]

This patch initializes flags in dma_async_tx_descriptor by the flags
passed from the caller when hidma_prep_dma_*(memcpy/memset) is called.

Cc: Joey Zheng <yu.zheng@hxt-semitech.com>
Reviewed-by: Sinan Kaya <okaya@kernel.org>
Signed-off-by: Shunyong Yang <shunyong.yang@hxt-semitech.com>
Signed-off-by: Vinod Koul <vkoul@kernel.org>