phy: Fix ptr_ret.cocci warnings

Use PTR_ERR_OR_ZERO rather than if(IS_ERR(...)) + PTR_ERR.

Generated by: scripts/coccinelle/api/ptr_ret.cocci

Signed-off-by: Vivek Gautam <vivek.gautam@codeaurora.org>
Cc: Kishon Vijay Abraham I <kishon@ti.com>
Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>