clk: si5341: Check for input clock presence and PLL lock on startup

After initializing the device, wait for it to report that the input
clock is present and the PLL has locked before declaring success.

Fixes: 3044a860

 ("clk: Add Si5341/Si5340 driver")
Signed-off-by: Robert Hancock <robert.hancock@calian.com>
Link: https://lore.kernel.org/r/20210325192643.2190069-5-robert.hancock@calian.com


Signed-off-by: Stephen Boyd <sboyd@kernel.org>