clk: samsung: exynos5420: Setup clocks before system suspend

Prior to suspending the system, we need to ensure that certain
clock source and gate registers are unmasked.

while at it, add these clks to save/restore list also.

Signed-off-by: Vikas Sajjan <vikas.sajjan@samsung.com>
Signed-off-by: Abhilash Kesavan <a.kesavan@samsung.com>
Signed-off-by: Tomasz Figa <t.figa@samsung.com>