serial: sh-sci: Don't check IRQ in verify port operation

The IRQ number can't be modified by the user as the port is fixed.
There's no need to check the new IRQ number as it will be ignored by the
core.

Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>