HID: mcp2221: fix 'cast to restricted __le16' sparse warnings

Use (__force __le16) cast for adc_values le16_to_cpu conversion to correct following sparse
warnings:

drivers/hid/hid-mcp2221.c:950:32: sparse: sparse: cast to restricted __le16
Reported-by: kernel test robot <lkp@intel.com>
Fixes: 960f9df7 ("HID: mcp2221: add ADC/DAC support via iio subsystem")
Signed-off-by: Matt Ranostay <matt.ranostay@konsulko.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

drivers/hid/hid-mcp2221.c

@@ -950,7 +950,7 @@ static int mcp2221_read_raw(struct iio_dev *indio_dev,
 		ret = mcp_chk_last_cmd_status(mcp);
 
 		if (!ret) {
-			*val = le16_to_cpu(mcp->adc_values[channel->address]);
+			*val = le16_to_cpu((__force __le16) mcp->adc_values[channel->address]);
 			if (*val >= BIT(10))
 				ret =  -EINVAL;
 			else