[nrf fromtree] samples: net: zperf: Optimize heap for nRF70 Series

Fine-tune the heap to get peak UDP (TX and RX) results but with minimal
heap consumption.

Signed-off-by: Chaitanya Tata <[email protected]>
(cherry picked from commit be4c79b)

Author: krish2718

samples/net/zperf/boards/nrf7002dk_nrf5340_cpuapp.conf

@@ -3,6 +3,9 @@ CONFIG_NET_PKT_RX_COUNT=28
 CONFIG_NET_PKT_TX_COUNT=27
 CONFIG_NET_BUF_RX_COUNT=28
 CONFIG_NET_BUF_TX_COUNT=54
+# reduces driver heap usage
+CONFIG_NRF70_RX_NUM_BUFS=16
+CONFIG_NRF_WIFI_DATA_HEAP_SIZE=50000
 CONFIG_NRF70_MAX_TX_AGGREGATION=4
 CONFIG_NRF70_QSPI_LOW_POWER=n