prj.conf: Increase CONFIG_POSIX_MAX_FDS to 10

Multiple sockets can be opened simultaneously, depending on timing.
The current limit of 4 FDs is too low when multiple socket users are
active across the stack. Since the modem supports up to 8 open sockets
and the Wi-Fi stack also uses sockets, increasing the limit to 10 is a
safer choice.

Signed-off-by: Simen S. Røstad <[email protected]>

app/prj.conf

@@ -10,6 +10,7 @@ CONFIG_RESET_ON_FATAL_ERROR=y
 CONFIG_LOG_MODE_DEFERRED=y
 CONFIG_LOG_BUFFER_SIZE=4096
 CONFIG_DK_LIBRARY=y
+CONFIG_POSIX_MAX_FDS=10
 CONFIG_PWM=y
 
 # Heap and stacks