The previous implementation of .handle_interrupt() did not take into
account the fact that all the interrupt status registers should be
acknowledged since multiple interrupt sources could be asserted.

Fix this by reading all the status registers before exiting with
IRQ_NONE or triggering the PHY state machine.

Fixes: 1d1ae3c6 ("net: phy: ti: implement generic .handle_interrupt() callback")
Reported-by: Sven Schuchmann <schuchmann@schleissheimer.de>
Signed-off-by: Ioana Ciornei <ioana.ciornei@nxp.com>
Link: https://lore.kernel.org/r/20210226153020.867852-1-ciorneiioana@gmail.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>