devm_of_phy_get_by_index() can fail for a number of reasons besides
probe deferral. It can for example return -ENOMEM if it runs out of
memory as it tries to allocate devres structures. Propagating only
-EPROBE_DEFER is problematic because it results in these legitimately
fatal errors being treated as "PHY not specified in DT".

What we really want is to ignore the optional PHYs only if they have not
been specified in DT. devm_of_phy_get_by_index() returns -ENODEV in this
case, so that's the special case that we need to handle. So we propagate
all errors, except -ENODEV, so that real failures will still cause the
driver to fail probe.
Signed-off-by: Thierry Reding <treding@nvidia.com>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Reviewed-by: Andrew Murray <andrew.murray@arm.com>
Cc: Thomas Petazzoni <thomas.petazzoni@bootlin.com>