ARM: dts: Add more opp levels in exynos5440

This patch updates cpu frequency level from 1500 to 800MHZ in steps
of 100MHZ. The corresponding voltage(in uV) is also added.

Signed-off-by: Amit Daniel Kachhap <amit.daniel@samsung.com>
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>