soc: nxp: rw: fix stack overflow in BLE samples

mbedtls is now used in BLE samples, increasing the stack depth needed
of the calling threads. This was causing stack overflows in several BLE
samples.
Increasing the BT_LONG_WQ_STACK stack size for peripheral_sc_only sample,
 and the SYSTEM_WORKQUEUE stack size for ibeacon sample.

Signed-off-by: Jasen Liu <jasen.liu@nxp.com>