Kernel/Net: Only enable interrupts after configuring the handler

We otherwise can lose interrupts that occurred between setting the
interrupt mask bits and registering the interrupt handler and therefore
enabling its interrupt.

Kernel/Net/Intel/E1000NetworkAdapter.cpp

@@ -206,6 +206,9 @@ UNMAP_AFTER_INIT ErrorOr<void> E1000NetworkAdapter::initialize(Badge<NetworkingM
     PCI::enable_memory_space(device_identifier());
     PCI::enable_bus_mastering(device_identifier());
 
+    // Ensure that interrupts are disabled during initialization.
+    out32(REG_INTERRUPT_MASK_CLEAR, 0xffff'ffff);
+
     dmesgln_pci(*this, "IO base: {}", m_registers_io_window);
     read_mac_address();
     auto const& mac = mac_address();
@@ -246,7 +249,6 @@ E1000NetworkAdapter::HardwareFeatures E1000NetworkAdapter::determine_hardware_fe
 UNMAP_AFTER_INIT ErrorOr<void> E1000NetworkAdapter::setup_interrupts()
 {
     out32(REG_INTERRUPT_RATE, 6000); // Interrupt rate of 1.536 milliseconds
-    out32(REG_INTERRUPT_MASK_SET, INTERRUPT_LSC | INTERRUPT_RXT0 | INTERRUPT_RXO);
 
     // FIXME: Support MSI-X on newer controllers. This requires allocating one or more MSI-X vectors
     //        and using the IVAR register to configure interrupt vector routing.
@@ -256,6 +258,8 @@ UNMAP_AFTER_INIT ErrorOr<void> E1000NetworkAdapter::setup_interrupts()
 
     m_interrupt_handler = TRY(InterruptHandler::create(*this, interrupt_number));
 
+    out32(REG_INTERRUPT_MASK_SET, INTERRUPT_LSC | INTERRUPT_RXT0 | INTERRUPT_RXO);
+
     return {};
 }