tests: dma: Update LLI pool size for sg test

The scatter gather test now does a transfer list of 4 and the LLI pool
config needs to be updated to match the new test requirement.

Signed-off-by: Tom Burdick <thomas.burdick@intel.com>
diff --git a/tests/drivers/dma/scatter_gather/boards/intel_adsp_cavs25.conf b/tests/drivers/dma/scatter_gather/boards/intel_adsp_cavs25.conf
new file mode 100644
index 0000000..b2dd497
--- /dev/null
+++ b/tests/drivers/dma/scatter_gather/boards/intel_adsp_cavs25.conf
@@ -0,0 +1 @@
+CONFIG_DMA_DW_LLI_POOL_SIZE=4