Input: xilinx_ps2 - fix kernel-doc for xps2_of_probe function

The existing comment block above the xps2_of_probe function
does not conform to the kernel-doc standard. This patch fixes the
documentation to match the expected kernel-doc format, which includes
a structured documentation header with param and return value.

Signed-off-by: Yang Li <yang.lee@linux.alibaba.com>
Reviewed-by: Michal Simek <michal.simek@amd.com>
Link: https://lore.kernel.org/r/20240301092115.123092-1-yang.lee@linux.alibaba.com
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>