The clk_init_data structures are never modified, make them const.

No functional changes.
Signed-off-by: Danila Tikhonov <danila@jiaxyga.com>
Link: https://lore.kernel.org/r/20240505201038.276047-3-danila@jiaxyga.comSigned-off-by: Bjorn Andersson <andersson@kernel.org>