video: fbdev: cirrusfb: Fix kernel-doc and set but not used warnings

Fix warnings:
- drop kernel-doc for the two debug functions to avoid the warnings
- delete unused code

v2:
  - Updated subject (Lee)
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Acked-by: Thomas Zimmermann <tzimmermann@suse.de>
Cc: Thomas Zimemrmann <tzimmermann@suse.de>
Cc: Sam Ravnborg <sam@ravnborg.org>
Cc: "Gustavo A. R. Silva" <gustavoars@kernel.org>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Saeed Mirzamohammadi <saeed.mirzamohammadi@oracle.com>
Cc: Jani Nikula <jani.nikula@intel.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Lee Jones <lee.jones@linaro.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20201128224114.1033617-28-sam@ravnborg.org

drivers/video/fbdev/cirrusfb.c

@@ -2463,8 +2463,6 @@ static void AttrOn(const struct cirrusfb_info *cinfo)
  */
 static void WHDR(const struct cirrusfb_info *cinfo, unsigned char val)
 {
-	unsigned char dummy;
-
 	if (is_laguna(cinfo))
 		return;
 	if (cinfo->btype == BT_PICASSO) {
@@ -2473,18 +2471,18 @@ static void WHDR(const struct cirrusfb_info *cinfo, unsigned char val)
 		WGen(cinfo, VGA_PEL_MSK, 0x00);
 		udelay(200);
 		/* next read dummy from pixel address (3c8) */
-		dummy = RGen(cinfo, VGA_PEL_IW);
+		RGen(cinfo, VGA_PEL_IW);
 		udelay(200);
 	}
 	/* now do the usual stuff to access the HDR */
 
-	dummy = RGen(cinfo, VGA_PEL_MSK);
+	RGen(cinfo, VGA_PEL_MSK);
 	udelay(200);
-	dummy = RGen(cinfo, VGA_PEL_MSK);
+	RGen(cinfo, VGA_PEL_MSK);
 	udelay(200);
-	dummy = RGen(cinfo, VGA_PEL_MSK);
+	RGen(cinfo, VGA_PEL_MSK);
 	udelay(200);
-	dummy = RGen(cinfo, VGA_PEL_MSK);
+	RGen(cinfo, VGA_PEL_MSK);
 	udelay(200);
 
 	WGen(cinfo, VGA_PEL_MSK, val);
@@ -2492,7 +2490,7 @@ static void WHDR(const struct cirrusfb_info *cinfo, unsigned char val)
 
 	if (cinfo->btype == BT_PICASSO) {
 		/* now first reset HDR access counter */
-		dummy = RGen(cinfo, VGA_PEL_IW);
+		RGen(cinfo, VGA_PEL_IW);
 		udelay(200);
 
 		/* and at the end, restore the mask value */
@@ -2800,9 +2798,9 @@ static void bestclock(long freq, int *nom, int *den, int *div)
 
 #ifdef CIRRUSFB_DEBUG
 
-/**
+/*
  * cirrusfb_dbg_print_regs
- * @base: If using newmmio, the newmmio base address, otherwise %NULL
+ * @regbase: If using newmmio, the newmmio base address, otherwise %NULL
  * @reg_class: type of registers to read: %CRT, or %SEQ
  *
  * DESCRIPTION:
@@ -2847,7 +2845,7 @@ static void cirrusfb_dbg_print_regs(struct fb_info *info,
 	va_end(list);
 }
 
-/**
+/*
  * cirrusfb_dbg_reg_dump
  * @base: If using newmmio, the newmmio base address, otherwise %NULL
  *