i2c: muxes: i2c-arb-gpio-challenge: Demote non-conformant kernel-doc headers

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

 drivers/i2c/muxes/i2c-arb-gpio-challenge.c:43: warning: Function parameter or member 'muxc' not described in 'i2c_arbitrator_select'
 drivers/i2c/muxes/i2c-arb-gpio-challenge.c:43: warning: Function parameter or member 'chan' not described in 'i2c_arbitrator_select'
 drivers/i2c/muxes/i2c-arb-gpio-challenge.c:86: warning: Function parameter or member 'muxc' not described in 'i2c_arbitrator_deselect'
 drivers/i2c/muxes/i2c-arb-gpio-challenge.c:86: warning: Function parameter or member 'chan' not described in 'i2c_arbitrator_deselect'
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Acked-by: Douglas Anderson <dianders@chromium.org>
Acked-by: Peter Rosin <peda@axentia.se>
Signed-off-by: Wolfram Sang <wsa@kernel.org>

drivers/i2c/muxes/i2c-arb-gpio-challenge.c

@@ -34,7 +34,7 @@ struct i2c_arbitrator_data {
 };
 
 
-/**
+/*
  * i2c_arbitrator_select - claim the I2C bus
  *
  * Use the GPIO-based signalling protocol; return -EBUSY if we fail.
@@ -77,7 +77,7 @@ static int i2c_arbitrator_select(struct i2c_mux_core *muxc, u32 chan)
 	return -EBUSY;
 }
 
-/**
+/*
  * i2c_arbitrator_deselect - release the I2C bus
  *
  * Release the I2C bus using the GPIO-based signalling protocol.