In CPU definitions we should not be explicilty naming peripheral modules to use
via USEMODULE (one should use FEATURES_PROVIDED instead).
Plus add missing cpu_init() and periph_init() methods.
This commit removes periph_hwrng support from the pic32mx cpu builds as
pic32mx does not have hwrng only pic32mz does.
U4RXREG is the RX buffer for UART4. U4RXR is the register for
controlling the input pin for UART4.
Signed-off-by: Francois Berder <francois.berder@imgtec.com>
Since the UART module takes control of RX and TX pins, there
is no need to configure the pins.
Signed-off-by: Francois Berder <francois.berder@imgtec.com>
