net: macb: Controller with module ID number 7 is GEM capable device

Modified the macb_configure_caps fucntion to include controllers
with module ID number 7 also as GEM device.

Signed-off-by: Punnaiah Choudary Kalluri <punnaia@xilinx.com>
Signed-off-by: Michal Simek <michal.simek@xilinx.com>