samples: wifi: shell: Reduce RX buffer to make room

For WPA supplicant to work properly it needs enough libc malloc, but
with recent changes might run out of memory, so, decrease RX buffers to
make room, as in our profiling we have seen 30 RX packets are enough,
this shouldn't impact the performance.

Fixes SHEL-1553 and SHEL-1512.

Signed-off-by: Krishna T <[email protected]>

Author: Krishna T

samples/wifi/shell/overlay-zperf.conf

@@ -1,9 +1,9 @@
 CONFIG_NET_ZPERF=y
 CONFIG_POSIX_MAX_FDS=16
 # Optimized networking settings for performance
-CONFIG_NET_PKT_RX_COUNT=32
+CONFIG_NET_PKT_RX_COUNT=30
 CONFIG_NET_PKT_TX_COUNT=32
-CONFIG_NET_BUF_RX_COUNT=32
+CONFIG_NET_BUF_RX_COUNT=30
 CONFIG_NET_BUF_TX_COUNT=64
 CONFIG_HEAP_MEM_POOL_SIZE=230000
 CONFIG_NET_BUF_DATA_SIZE=1100