drm/i915: fix comment on I915_{READ, WRITE}_FW

#undef __raw_write

/* These are untraced mmio-accessors that are only valid to be used inside

 * critical sections inside IRQ handlers where forcewake is explicitly

 * critical sections, such as inside IRQ handlers, where forcewake is explicitly

 * controlled.

 *

 * Think twice, and think again, before using these.

 * Note: Should only be used between intel_uncore_forcewake_irqlock() and

 * intel_uncore_forcewake_irqunlock().

 *

 * As an example, these accessors can possibly be used between:

 *

 * spin_lock_irq(&dev_priv->uncore.lock);

 * intel_uncore_forcewake_get__locked();

 *

 * and

 *

 * intel_uncore_forcewake_put__locked();

 * spin_unlock_irq(&dev_priv->uncore.lock);

 *

 *

 * Note: some registers may not need forcewake held, so

 * intel_uncore_forcewake_{get,put} can be omitted, see

 * intel_uncore_forcewake_for_reg().

 *

 * Certain architectures will die if the same cacheline is concurrently accessed

 * by different clients (e.g. on Ivybridge). Access to registers should

 * therefore generally be serialised, by either the dev_priv->uncore.lock or

 * a more localised lock guarding all access to that bank of registers.

 */

#define I915_READ_FW(reg__) __raw_i915_read32(dev_priv, (reg__))

#define I915_WRITE_FW(reg__, val__) __raw_i915_write32(dev_priv, (reg__), (val__))