net: qcom/emac: Fix module autoload for OF registration

If the driver is built as a module, autoload won't work because the module
alias information is not filled. So user-space can't match the registered
device with the corresponding module.

Export the module alias information using the MODULE_DEVICE_TABLE() macro.

Before this patch:

$ modinfo drivers/net/ethernet/qualcomm/emac/qcom-emac.ko | grep alias
alias:          platform:qcom-emac

After this patch:

$ modinfo drivers/net/ethernet/qualcomm/emac/qcom-emac.ko | grep alias
alias:          platform:qcom-emac
alias:          of:N*T*Cqcom,fsm9900-emacC*
alias:          of:N*T*Cqcom,fsm9900-emac

Signed-off-by: Javier Martinez Canillas <javier@osg.samsung.com>
Acked-by: Timur Tabi <timur@codeaurora.org>
Signed-off-by: David S. Miller <davem@davemloft.net>