Input: ili210x - fix ili251x_read_touch_data() return value

Input: ili210x - fix ili251x_read_touch_data() return value

The caller of this function treats all non-zero values as an error, so
the return value of i2c_master_recv() cannot be returned directly.

This fixes touch reporting when there are more than 6 active touches.

Fixes: ef536abd3afd1 ("Input: ili210x - define and use chip operations structure")
Signed-off-by: John Keeping <jkeeping@inmusicbrands.com>
Link: https://lore.kernel.org/r/20240523085624.2295988-1-jkeeping@inmusicbrands.com
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>