clk: divider: Introduce CLK_DIVIDER_EVEN_INTEGERS flag

clk: divider: Introduce CLK_DIVIDER_EVEN_INTEGERS flag

Add CLK_DIVIDER_EVEN_INTEGERS flag to support divisor of 2, 4, 6, etc.
The same divisor can be done using a table, which would be big and
wasteful for a clock dividor of width 8 (256 entries).

Require increasing flags size from u8 to u16 because
CLK_DIVIDER_EVEN_INTEGERS is the eighth flag. u16 is used inside struct
clk_divider; `unsigned long` is used for function arguments.

Signed-off-by: Théo Lebrun <theo.lebrun@bootlin.com>
Link: https://lore.kernel.org/r/20241007-mbly-clk-v5-3-e9d8994269cb@bootlin.com
Signed-off-by: Stephen Boyd <sboyd@kernel.org>