sunxi: restore PHYLIB for CONFIG_SUN4I_EMAC users

due misnaming of CONFIG_SUN4I_EMAC in include/configs/sunxi-common.h,
likely missed in:
	commit 3146f0c0 ("Move PHYLIB to Kconfig")

Signed-off-by: Artturi Alm <artturi.alm@gmail.com>
Reviewed-by: Jagan Teki <jagan@openedev.com>