drm/i915: Fix i915_switch_context() argument name in kerneldoc

While reading some code, out of boredom, stumbled on a tiny tiny fix.
Signed-off-by: Damien Lespiau <damien.lespiau@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/i915_gem_context.c

@@ -758,7 +758,7 @@ static int do_switch(struct intel_ring_buffer *ring,
  * i915_switch_context() - perform a GPU context switch.
  * @ring: ring for which we'll execute the context switch
  * @file_priv: file_priv associated with the context, may be NULL
- * @id: context id number
+ * @to: the context to switch to
  *
  * The context life cycle is simple. The context refcount is incremented and
  * decremented by 1 and create and destroy. If the context is in use by the GPU,