Kernel: Make all Spinlocks use u8 for storage, remove template

The default template argument is only used in one place, and it
looks like it was probably just an oversight. The rest of the Kernel
code all uses u8 as the type. So lets make that the default and remove
the unused template argument, as there doesn't seem to be a reason to
allow the size to be customizable.

Kernel/Graphics/Console/GenericFramebufferConsole.h

@@ -47,6 +47,6 @@ protected:
     virtual u8* framebuffer_data() = 0;
     void clear_glyph(size_t x, size_t y);
     size_t m_pitch;
-    mutable Spinlock<u8> m_lock;
+    mutable Spinlock m_lock;
 };
 }