ARM: shmobile: lager dts: Add da9210 regulator interrupt

The da9210 regulator is connected to IRQ2. Reflect this in its device
node, so the driver can use it when it gains interrupt support.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>