video: exynos_fb: Make fimd_ctrl global

fimd_ctrl variable was redundantly defined across all the functions in
the driver even though it contains just the same address. We make it
global and initialize it in exynos_fimd_lcd_init. From then on, other
funtions can use the data in the global variable.

Signed-off-by: Ajay Kumar <ajaykumar.rs@samsung.com>
Signed-off-by: Minkyu Kang <mk7.kang@samsung.com>