clk: renesas: Do not test unsigned variable to be less than 0

clk: renesas: Do not test unsigned variable to be less than 0

In rcar_clk_set_rate64_div_table the unsigned variable 'value' is used
to receive the return value from rcar_clk_get_table_val which returns an
int and then attempts to test for being less than 0, which can never be
true. Instead declare value as an int so the code can behave as
expected. Also remove initial values from 'value' and 'div' as they are
not needed.

This issue was found by Smatch.

Signed-off-by: Andrew Goodbody <andrew.goodbody@linaro.org>
Reviewed-by: Marek Vasut <marek.vasut+renesas@mailbox.org>