cpu, sam0_common: fix unused parameter in periph/spi
        cpu, kinetis_common: fix unused parameter in periph/spi
        cpu, cc2538: fix unused param in periph/i2c
        cpu, cc2538: fix unused param in periph/spi
        cpu, sam3: fix unused param in periph/spi
        cpu, stm32_common: fix unused param in periph/pm
        cpu, stm32f3: fix unused params in periph/i2c
        cpu, nrf5x_common: fix unused param in periph/gpio
        cpu, nrf5x_common: fix unused param in periph/spi
        cpu, lpc2387: fix unused params in periph/spi
        cpu, cc2538: fix unused params in radio/netdev
        cpu, cc2650: fix unused params in periph/uart
        cpu, lm4f120: fix unused param in periph/spi
        cpu, lm4f120: fix unused params in periph/timer
        cpu, lm4f120: fix unused params in periph/uart
        cpu, stm32_common: fix unused params in periph/dac
        cpu, stm32l0: fix unused params in periph/i2c
        cpu, msp430fxyz: fix unused params in periph/uart
        cpu, mips: fix unused params
        cpu, cc430: fix unused-params in periph/timer
        cpu, msp430fxyz: fix unused params in periph/spi
        drivers, cc2420: fix unused param
        cpu, mips32r2_common: fix unused params in periph/timer
        cpu, cc2538: fix unused-param in periph/i2c
        cpu, mips32r2_common: fix unused-param in periph/timer
        cpu, msp430fxyz: fix unused params in periph/timer
        cpu, atmega_common: fix unused params in periph/spi
        driver, nrfmin: fix unused params
        cpu, cc2538_rf: fix unused params
        driver, netdev_ieee802514: fix unused param
        cpu, mip_pic32m: fix unused params
        cpu, lpc2387: fix unused params in periph/pwm
        tests/driver_sdcard_spi: fix unused params
        cpu, sam3: fix unused param in periph/pwm
        tests/driver_dynamixel: fix unused params, and style issues
        cpu, cc430: fix unused param in periph/rtc
        cpu, atmega_common: fix unused params in periph/i2c