memory: samsung: exynos5422-dmc: Correct function names in kerneldoc

memory: samsung: exynos5422-dmc: Correct function names in kerneldoc

Correct kerneldoc to fix W=1 warnings:

    drivers/memory/samsung/exynos5422-dmc.c:290: warning:
        expecting prototype for find_target_freq_id(). Prototype was for find_target_freq_idx() instead
    drivers/memory/samsung/exynos5422-dmc.c:1015: warning:
        expecting prototype for exynos5_dmc_align_initial_frequency(). Prototype was for exynos5_dmc_align_init_freq() instead

Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>
Reviewed-by: Lukasz Luba <lukasz.luba@arm.com>
Link: https://lore.kernel.org/r/20210206111715.20774-1-krzk@kernel.org