Input: fsia6b - suppress buffer truncation warning for phys

Switch the driver to use scnprintf() to avoid warnings about potential
truncation of "phys" field which we can tolerate.

Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202501020303.1WtxWWTu-lkp@intel.com/


Signed-off-by: Markus Koch <markus@notsyncing.net>
Link: https://lore.kernel.org/r/20250602175710.61583-4-markus@notsyncing.net


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