uvesafb: improve parameter handling.

1) Now module_param(..., invbool, ...) requires a bool, and similarly
   module_param(..., bool, ...) allows it, change pmi_setpal to a bool.
2) #define param_get_scroll to NULL, since it can never be called (perm
   argument to module_param_named is 0).
3) Return -EINVAL from param_set_scroll if the value is bad, so it's
   reported.

Note that I don't think the old fb_get_options() is required for new
drivers: the parameters automatically work as uvesafb.XXX=... anyway.
Acked-by: Michał Januszewski <spock@gentoo.org>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

drivers/video/uvesafb.c

@@ -45,7 +45,7 @@ static struct fb_fix_screeninfo uvesafb_fix __devinitdata = {
 static int mtrr		__devinitdata = 3; /* enable mtrr by default */
 static int blank	= 1;		   /* enable blanking by default */
 static int ypan		= 1; 		 /* 0: scroll, 1: ypan, 2: ywrap */
-static int pmi_setpal	__devinitdata = 1; /* use PMI for palette changes */
+static bool pmi_setpal	__devinitdata = true; /* use PMI for palette changes */
 static int nocrtc	__devinitdata; /* ignore CRTC settings */
 static int noedid	__devinitdata; /* don't try DDC transfers */
 static int vram_remap	__devinitdata; /* set amt. of memory to be used */
@@ -2002,11 +2002,7 @@ static void __devexit uvesafb_exit(void)
 
 module_exit(uvesafb_exit);
 
-static int param_get_scroll(char *buffer, struct kernel_param *kp)
-{
-	return 0;
-}
-
+#define param_get_scroll NULL
 static int param_set_scroll(const char *val, struct kernel_param *kp)
 {
 	ypan = 0;
@@ -2017,6 +2013,8 @@ static int param_set_scroll(const char *val, struct kernel_param *kp)
 		ypan = 1;
 	else if (!strcmp(val, "ywrap"))
 		ypan = 2;
+	else
+		return -EINVAL;
 
 	return 0;
 }