ARM: dts: orion5x: fix number of sata port for linkstation ls-gl

Bug report from Debian [0] shows there's minor changed model of
Linkstation LS-GL that uses the 2nd SATA port of the SoC.
So it's necessary to enable two SATA ports, though for that specific
model only the 2nd one is used.

[0] https://bugs.debian.org/845611

Fixes: b1742ffa

 ("ARM: dts: orion5x: add device tree for buffalo linkstation ls-gl")
Reported-by: Ryan Tandy <ryan@nardis.ca>
Tested-by: Ryan Tandy <ryan@nardis.ca>
Signed-off-by: Roger Shimizu <rogershimizu@gmail.com>
Signed-off-by: Gregory CLEMENT <gregory.clement@free-electrons.com>