arm:replace ifdef's by runtime checks in the lan8710a driver.
arm:replace ifdef's by runtime checks in the lan8710a driver.

Change-Id: I1f345240b88362658e987a85f1642324471119c3

veritas-shine/minix3-rpi,veritas-shine/minix3-rpi,veritas-shine/minix3-rpi,veritas-shine/minix3-rpi,veritas-shine/minix3-rpi,veritas-shine/minix3-rpi,veritas-shine/minix3-rpi,veritas-shine/minix3-rpi