ARM: rmobile: salvator-x: Enable SCIF2 clock

There are two UARTs on the board, so enable the clock for the
second one as well.

Signed-off-by: Marek Vasut <marek.vasut+renesas@gmail.com>
Cc: Hiroyuki Yokoyama <hiroyuki.yokoyama.vx@renesas.com>
Cc: Nobuhiro Iwamatsu <iwamatsu@nigauri.org>