samples: net: zperf: fix NRF_WIFI_DATA_HEAP_SIZE

Commit e33d9ee incorrectly stated that:
 > Now that nRF70 by default uses zero-copy fine-tune the configuration
   to get optimal memory while getting peak throughputs.

This is incorrect since `NRF_WIFI_ZERO_COPY_TX` is only enabled by
default for the nRF54L series. Update the data heap size so that the
smaller value is only used when `NRF_WIFI_ZERO_COPY_TX` is enabled.

Signed-off-by: Jordan Yates <[email protected]>

Author: JordanYates

samples/net/zperf/Kconfig

@@ -1,8 +1,6 @@
 # Copyright 2023 NXP
 # SPDX-License-Identifier: Apache-2.0
 
-source "Kconfig.zephyr"
-
 config NET_SAMPLE_CODE_RELOCATE
 	bool "Relocate networking code into RAM"
 	select CODE_DATA_RELOCATION
@@ -27,3 +25,9 @@ if USB_DEVICE_STACK_NEXT
 # tree, you cannot use them in your own application.
 	source "samples/subsys/usb/common/Kconfig.sample_usbd"
 endif
+
+configdefault NRF_WIFI_DATA_HEAP_SIZE
+	default 30000 if NRF_WIFI_ZERO_COPY_TX
+	default 50000
+
+source "Kconfig.zephyr"

samples/net/zperf/boards/nrf7002dk_nrf5340_cpuapp.conf

@@ -4,7 +4,6 @@ CONFIG_NET_PKT_TX_COUNT=28
 CONFIG_NET_BUF_RX_COUNT=28
 CONFIG_NET_BUF_TX_COUNT=28
 CONFIG_NRF70_RX_NUM_BUFS=16
-CONFIG_NRF_WIFI_DATA_HEAP_SIZE=30000
 CONFIG_NET_PKT_BUF_TX_DATA_POOL_SIZE=20000
 CONFIG_NRF70_MAX_TX_AGGREGATION=4
 CONFIG_NRF70_QSPI_LOW_POWER=n