phy: fix returnvar.cocci warnings

Remove unneeded variables when "0" can be returned.

Generated by: scripts/coccinelle/misc/returnvar.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>