meson: clk: Rename register names according to Amlogic datasheet

Signed-off-by: Alexander Müller <serveralex@gmail.com>
Signed-off-by: Michael Turquette <mturquette@baylibre.com>
Link: lkml.kernel.org/r/1472319654-59048-4-git-send-email-serveralex@gmail.com