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

 drivers/input/touchscreen/imx6ul_tsc.c: In function ‘adc_irq_fn’:
 drivers/input/touchscreen/imx6ul_tsc.c:307:6: warning: variable ‘value’ set but not used [-Wunused-but-set-variable]
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Reviewed-by: Haibo Chen <haibo.chen@nxp.com>
Link: https://lore.kernel.org/r/20201112110204.2083435-6-lee.jones@linaro.orgSigned-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>