Kernel: Fix E1000{,E} driver for older qemu versions

This patch adds clearing of *Interrupt Cause Registers*, which allows
older qemu versions to send new interrupts. Apparently this is not
needed on newer releases.

kernel/kernel/Networking/E1000/E1000.cpp

@@ -308,6 +308,8 @@ namespace Kernel
 			descriptor.status = 0;
 			write32(REG_RDT0, rx_current);
 		}
+
+		write32(REG_ICR, 0xFFFFFFFF);
 	}
 
 }