clk: fixed-rate: Remove redundant if statement

(np) is always true when (dev || !np) is false, so just remove
the check.

Signed-off-by: Li Zhengyu <lizhengyu3@huawei.com>
Link: https://lore.kernel.org/r/20220509092102.140520-1-lizhengyu3@huawei.com
Signed-off-by: Stephen Boyd <sboyd@kernel.org>