qcom: subsys-pil-tz: Add device pointer to call for allocating DMA memory

Replace sending NULL with the device pointer as the first
parameter for the dma_alloc_attrs function. Doing this
corrects this call failing on 64 bit.

Change-Id: I385197e3596695f1646fd9072f178dac1f15d6e5
Signed-off-by: Deepak Katragadda <dkatraga@codeaurora.org>