phy: zynqmp: Add debugfs support

Add support for printing some basic status information to debugfs. This
is helpful when debugging phy consumers to make sure they are configuring
the phy appropriately.

Signed-off-by: Sean Anderson <sean.anderson@linux.dev>
Link: https://lore.kernel.org/r/20240628205540.3098010-6-sean.anderson@linux.dev


Signed-off-by: Vinod Koul <vkoul@kernel.org>