net: qcom/emac: don't try to claim clocks on ACPI systems

On ACPI systems, clocks are not available to drivers directly.  They are
handled exclusively by ACPI and/or firmware, so there is no clock driver.
Calls to clk_get() always fail, so we should not even attempt to claim
any clocks on ACPI systems.

Signed-off-by: Timur Tabi <timur@codeaurora.org>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>