ARM: EXYNOS: Increase virtual framebuffer size on Universal C210 board

Increase framebuffer virtual size to enable display panning.

Signed-off-by: Sylwester Nawrocki <s.nawrocki@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>