phy: Allow a NULL phy name for devm_phy_get()

phy: Allow a NULL phy name for devm_phy_get()

For a single PHY, there's no reason to have a phy-names entry in DT.
The DT specific get functions allow for this already, but devm_phy_get()
WARNs in this case. Other subsystems also don't warn in their get
functions. Let's drop the WARN for DT case in devm_phy_get().

Cc: Kishon Vijay Abraham I <kishon@ti.com>
Cc: Vinod Koul <vkoul@kernel.org>
Signed-off-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20210414135525.3535787-1-robh@kernel.org
Signed-off-by: Vinod Koul <vkoul@kernel.org>