drivers: usb: dwc3: remove devm_zalloc from linux_compact

devm_zalloc() is already defined in dm/device.h header, so
devm_zalloc can be removed from linux_compact.h beader file.

Signed-off-by: Mugunthan V N <mugunthanvnm@ti.com>
Signed-off-by: Michal Simek <michal.simek@xilinx.com>