clk: samsung: exynos4: add support for MOUT_HDMI and MOUT_MIXER clocks

This patch adds support for exporting mout_hdmi and mout_mixer to device
tree. Access to those clocks is required to correctly setup HDMI module
on Exynos 4210 and 4x12 SoCs.

Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
CC: Mike Turquette <mturquette@linaro.org>
CC: Tomasz Figa <t.figa@samsung.com>
Signed-off-by: Tomasz Figa <tomasz.figa@gmail.com>