vsprintf: Avoid confusion between invalid address and value

We are able to detect invalid values handled by %p[iI] printk specifier.
The current error message is "invalid address". It might cause confusion
against "(efault)" reported by the generic valid_pointer_address() check.

Let's unify the style and use the more appropriate error code description
"(einval)".

Link: http://lkml.kernel.org/r/20190417115350.20479-10-pmladek@suse.com
To: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: "Tobin C . Harding" <me@tobin.cc>
Cc: Joe Perches <joe@perches.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
Cc: linux-kernel@vger.kernel.org
Reviewed-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Petr Mladek <pmladek@suse.com>

Documentation/core-api/printk-formats.rst

@@ -64,6 +64,7 @@ might be printed instead of the unreachable information::
 
 	(null)	 data on plain NULL address
 	(efault) data on invalid address
+	(einval) invalid data on a valid address
 
 Plain Pointers
 --------------

lib/vsprintf.c

@@ -1511,7 +1511,7 @@ char *ip_addr_string(char *buf, char *end, const void *ptr,
 		case AF_INET6:
 			return ip6_addr_string_sa(buf, end, &sa->v6, spec, fmt);
 		default:
-			return string_nocheck(buf, end, "(invalid address)", spec);
+			return string_nocheck(buf, end, "(einval)", spec);
 		}}
 	}