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 main stack size for common samples, but also the shell
stack size for samples calling bt API from the shell thread like the
bt shell.

Signed-off-by: Axel Le Bourhis <axel.lebourhis@nxp.com>