The existing heap starts at the beginning of SPIRAM which is also occupied
by the WiFi stack if CONFIG_ESP32_WIFI_NET_ALLOC_SPIRAM is enabled. This
results in memory corruption.
Update the linker description to add a _spiram_heap_start symbol and add a
KConfig size option to allow the SPIRAM stack to be correctly located and
sized. Requires matching commit in hal_espressif.
Fixes: 61359
Signed-off-by: Eric Holmberg <eric.holmberg@northriversystems.co.nz>
