Input: da7280 - fix missing error test

An "if" testing for error condition has accidentally been dropped from
the code.

Reported-by: kernel test robot <lkp@intel.com>
Fixes: cd3f6098 ("Input: new da7280 haptic driver")
Reviewed-by: Roy Im <Roy.Im.Opensource@diasemi.com>
Link: https://lore.kernel.org/r/X9j8lGFgijzHyYZZ@google.com


Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>