misc: ti_fpc202: fix off-by-one error in port ID bounds check

misc: ti_fpc202: fix off-by-one error in port ID bounds check

FPC202_NUM_PORTS is 2, valid port IDs should be 0 and 1. A port_id of 2
would incorrectly pass the check, potentially causing out-of-bounds
access to the port-related arrays.

Found by code review, compile pass.

Fixes: 1e5c9b1efa1c ("misc: add FPC202 dual port controller driver")
Signed-off-by: Felix Gu <ustc.gu@gmail.com>
Reviewed-by: Romain Gantois <romain.gantois@bootlin.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Andi Shyti <andi.shyti@kernel.org>
Link: https://patch.msgid.link/20260221-fp202-v1-1-4d28cb8b28fb@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>