clk: si5341: Add sysfs properties to allow checking/resetting device faults

Add sysfs property files to allow viewing the current and latched states of
the input present and PLL lock bits, and allow resetting the latched fault
state. This allows manual checks or automated userspace polling for faults
occurring after initialization.

Signed-off-by: Robert Hancock <robert.hancock@calian.com>
Link: https://lore.kernel.org/r/20210325192643.2190069-10-robert.hancock@calian.com
Signed-off-by: Stephen Boyd <sboyd@kernel.org>