drm/i915: Add pretty printer for modparams

We dump modparams in few places (debugfs, gpu_error) using different
functions. Lets add reusable function to avoid code duplication.

add/remove: 1/0 grow/shrink: 0/2 up/down: 1096/-2339 (-1243)
Function                                     old     new   delta
i915_params_dump                               -    1096   +1096
i915_capabilities                           1353     185   -1168
i915_error_state_to_str                     5507    4336   -1171
Total: Before=1285716, After=1284473, chg -0.10%

v2: use forward decl rather than include (Chris)

Signed-off-by: Michal Wajdeczko <michal.wajdeczko@intel.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Link: https://patchwork.freedesktop.org/patch/msgid/20171219114346.26308-3-michal.wajdeczko@intel.com
diff --git a/drivers/gpu/drm/i915/i915_debugfs.c b/drivers/gpu/drm/i915/i915_debugfs.c
index e384e28..c4780f0 100644
--- a/drivers/gpu/drm/i915/i915_debugfs.c
+++ b/drivers/gpu/drm/i915/i915_debugfs.c
@@ -37,23 +37,6 @@ static inline struct drm_i915_private *node_to_i915(struct drm_info_node *node)
 	return to_i915(node->minor->dev);
 }
 
-static __always_inline void seq_print_param(struct seq_file *m,
-					    const char *name,
-					    const char *type,
-					    const void *x)
-{
-	if (!__builtin_strcmp(type, "bool"))
-		seq_printf(m, "i915.%s=%s\n", name, yesno(*(const bool *)x));
-	else if (!__builtin_strcmp(type, "int"))
-		seq_printf(m, "i915.%s=%d\n", name, *(const int *)x);
-	else if (!__builtin_strcmp(type, "unsigned int"))
-		seq_printf(m, "i915.%s=%u\n", name, *(const unsigned int *)x);
-	else if (!__builtin_strcmp(type, "char *"))
-		seq_printf(m, "i915.%s=%s\n", name, *(const char **)x);
-	else
-		BUILD_BUG();
-}
-
 static int i915_capabilities(struct seq_file *m, void *data)
 {
 	struct drm_i915_private *dev_priv = node_to_i915(m->private);
@@ -67,9 +50,7 @@ static int i915_capabilities(struct seq_file *m, void *data)
 	intel_device_info_dump_flags(info, &p);
 
 	kernel_param_lock(THIS_MODULE);
-#define PRINT_PARAM(T, x, ...) seq_print_param(m, #x, #T, &i915_modparams.x);
-	I915_PARAMS_FOR_EACH(PRINT_PARAM);
-#undef PRINT_PARAM
+	i915_params_dump(&i915_modparams, &p);
 	kernel_param_unlock(THIS_MODULE);
 
 	return 0;