drivers: Remove unused parameter warning

This patch fixes the unused parameter warning found at the
following drivers:

- adc_ti_adc108s102.c
- gpio_dw.c
- gpio_k64.c
- exti_stm32.c
- pinmux_dev_atmel_sam3x.c
- pinmux_dev_k64.c
- pinmux_dev_stm32.c
- uart_atmel_sam3.c

Change-Id: I76a17d19176683130d57e8f48e5195e7785060f3
Signed-off-by: Flavio Santes <flavio.santes@intel.com>
8 files changed