Input: cypress_ps2 - clean up setting reporting rate

Casting an integer field containing desired rate to a pointer to bytes
works on little endian architectures where the driver is used, but not
a good practice. Use a temporary of proper type instead.

Link: https://lore.kernel.org/r/20240628224728.2180126-1-dmitry.torokhov@gmail.com


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