Updated Serial Flash interface & Network buffer classes to avoid warnings and improve robustness. Fixed issue with mbed_overrides trying to use an old implementation of cy_serial_flash_init() function.
Remove some (Cypress-proprietary) BSP interfaces and hardware initialization
from the BSPs which is better implemented by a library or application firmware.
Move some remaining functionality from common to the individual targets.
Don't malloc during wifi initialization, as that could cause double allocation in some cases.
The thread stack will be allocated by cy_rtos_thread_start if necessary.