clk: return unsigned int in dummy non-OF of_clk_get_parent_count()

clk: return unsigned int in dummy non-OF of_clk_get_parent_count()

In the commit 59414471f7426 ("clk: Make of_clk_get_parent_count() return
unsigned ints") of_clk_get_parent_count has been modified to return
unsigned int. There is also a dummy implementation of the same function
for configs without CONFIG_OF. For the consistency it should be updated
as well.

Signed-off-by: Rafał Miłecki <rafal@milecki.pl>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>