The driver was initially written for exynos4 but the driver is used
also for exynos5.

Change the function prefix name exynos4 -> exynos
Signed-off-by: NDaniel Lezcano <daniel.lezcano@linaro.org>
Reviewed-by: NViresh Kumar <viresh.kumar@linaro.org>
Reviewed-by: NBartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
Reviewed-by: NTomasz Figa <t.figa@samsung.com>
Signed-off-by: NKukjin Kim <kgene.kim@samsung.com>