kernel/PCI: Add bit enum for the Command field

kernel/src/arch/PCI.h

@@ -27,6 +27,20 @@ namespace PCI
         InterruptLine = 0x3c,
     };
 
+    enum CommandField : u16
+    {
+        CMD_IO_SPACE = 1 << 0,
+        CMD_MEMORY_SPACE = 1 << 1,
+        CMD_BUS_MASTER = 1 << 2,
+        CMD_SPECIAL_CYCLES = 1 << 3,
+        CMD_MEMORY_WRITE_AND_INVALIDATE = 1 << 4,
+        CMD_VGA_PALETTE_SNOOP = 1 << 5,
+        CMD_PARITY_ERROR_RESPONSE = 1 << 6,
+        CMD_SERR = 1 << 8,
+        CMD_FAST_BACK_TO_BACK = 1 << 9,
+        CMD_INTERRUPT_DISABLE = 1 << 10,
+    };
+
     struct BAR
     {
       public: