ARM: 7392/1: CLKDEV: Optimize clk_find()

clk_find must return as soon as it gets the correct clock. Currently it check
all clocks until it found a lookup with both dev_id and con_id matching.

If only one of them is passed, then we don't actually need to wait for both of
them to match. We can quit as soon as the requested id (dev_id or con_id)
matches.

Signed-off-by: Viresh Kumar <viresh.kumar@st.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>