drm/i915: move module parameters into a struct, in a new file

With 20+ module parameters, I think referring to them via a struct
improves clarity over just having a bunch of globals. While at it, move
the parameter initialization and definitions into a new file
i915_params.c to reduce clutter in i915_drv.c.

Apart from the ill-named i915_enable_rc6, i915_enable_fbc and
i915_enable_ppgtt parameters, for which we lose the "i915_" prefix
internally, the module parameters now look the same both on the kernel
command line and in code. For example, "i915.modeset".

The downsides of the change are losing static on a couple of variables
and not having the initialization and module_param_named() right next to
each other. On the other hand, all module parameters are now defined in
one place at i915_params.c. Plus you can do this to find all module
parameter references:

$ git grep "i915\." -- drivers/gpu/drm/i915

v2:
- move the definitions into a new file
- s/i915_params/i915/
- make i915_try_reset i915.reset, for consistency

Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
diff --git a/drivers/gpu/drm/i915/intel_panel.c b/drivers/gpu/drm/i915/intel_panel.c
index 9f83ab0..f1ee2c4 100644
--- a/drivers/gpu/drm/i915/intel_panel.c
+++ b/drivers/gpu/drm/i915/intel_panel.c
@@ -323,13 +323,6 @@
 	pipe_config->gmch_pfit.lvds_border_bits = border;
 }
 
-static int i915_panel_invert_brightness;
-MODULE_PARM_DESC(invert_brightness, "Invert backlight brightness "
-	"(-1 force normal, 0 machine defaults, 1 force inversion), please "
-	"report PCI device ID, subsystem vendor and subsystem device ID "
-	"to dri-devel@lists.freedesktop.org, if your machine needs it. "
-	"It will then be included in an upcoming module version.");
-module_param_named(invert_brightness, i915_panel_invert_brightness, int, 0600);
 static u32 intel_panel_compute_brightness(struct intel_connector *connector,
 					  u32 val)
 {
@@ -339,10 +332,10 @@
 
 	WARN_ON(panel->backlight.max == 0);
 
-	if (i915_panel_invert_brightness < 0)
+	if (i915.invert_brightness < 0)
 		return val;
 
-	if (i915_panel_invert_brightness > 0 ||
+	if (i915.invert_brightness > 0 ||
 	    dev_priv->quirks & QUIRK_INVERT_BRIGHTNESS) {
 		return panel->backlight.max - val;
 	}
@@ -808,13 +801,13 @@
 	struct drm_i915_private *dev_priv = dev->dev_private;
 
 	/* Assume that the BIOS does not lie through the OpRegion... */
-	if (!i915_panel_ignore_lid && dev_priv->opregion.lid_state) {
+	if (!i915.panel_ignore_lid && dev_priv->opregion.lid_state) {
 		return ioread32(dev_priv->opregion.lid_state) & 0x1 ?
 			connector_status_connected :
 			connector_status_disconnected;
 	}
 
-	switch (i915_panel_ignore_lid) {
+	switch (i915.panel_ignore_lid) {
 	case -2:
 		return connector_status_connected;
 	case -1: