i2c: busses: i2c-nomadik: Fix formatting issue pertaining to 'timeout'

Fixes the following W=1 kernel build warning(s):

 drivers/i2c/busses/i2c-nomadik.c:184: warning: Function parameter or member 'timeout' not described in 'nmk_i2c_dev'

Signed-off-by: Lee Jones <lee.jones@linaro.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Wolfram Sang <wsa@kernel.org>