clk: ingenic: Fix doc of ingenic_cgu_div_info

The 'div' field does not represent a number of bits used to divide
(understand: right-shift) the divider, but a number itself used to
divide the divider.

Signed-off-by: Paul Cercueil <paul@crapouillou.net>
Signed-off-by: Maarten ter Huurne <maarten@treewalker.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>