Use 'E' instead of 'X' for unsigned module taint flag.

Takashi Iwai <tiwai@suse.de> says:
> The letter 'X' has been already used for SUSE kernels for very long
> time, to indicate the external supported modules.  Can the new flag be
> changed to another letter for avoiding conflict...?
> (BTW, we also use 'N' for "no support", too.)

Note: this code should be cleaned up, so we don't have such maps in
three places!
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

Documentation/ABI/testing/sysfs-module

@@ -49,4 +49,4 @@ Description:	Module taint flags:
 			O - out-of-tree module
 			F - force-loaded module
 			C - staging driver module
-			X - unsigned module
+			E - unsigned module

Documentation/module-signing.txt

@@ -54,7 +54,7 @@ This has a number of options available:
      If this is off (ie. "permissive"), then modules for which the key is not
      available and modules that are unsigned are permitted, but the kernel will
      be marked as being tainted, and the concerned modules will be marked as
-     tainted, shown with the character 'X'.
+     tainted, shown with the character 'E'.
 
      If this is on (ie. "restrictive"), only modules that have a valid
      signature that can be verified by a public key in the kernel's possession

Documentation/oops-tracing.txt

@@ -265,7 +265,7 @@ characters, each representing a particular tainted value.
 
  13: 'O' if an externally-built ("out-of-tree") module has been loaded.
 
- 14: 'X' if an unsigned module has been loaded in a kernel supporting
+ 14: 'E' if an unsigned module has been loaded in a kernel supporting
      module signature.
 
 The primary reason for the 'Tainted: ' string is to tell kernel

kernel/module.c

@@ -1014,7 +1014,7 @@ static size_t module_flags_taint(struct module *mod, char *buf)
 	if (mod->taints & (1 << TAINT_CRAP))
 		buf[l++] = 'C';
 	if (mod->taints & (1 << TAINT_UNSIGNED_MODULE))
-		buf[l++] = 'X';
+		buf[l++] = 'E';
 	/*
 	 * TAINT_FORCED_RMMOD: could be added.
 	 * TAINT_UNSAFE_SMP, TAINT_MACHINE_CHECK, TAINT_BAD_PAGE don't

kernel/panic.c

@@ -210,7 +210,7 @@ static const struct tnt tnts[] = {
 	{ TAINT_CRAP,			'C', ' ' },
 	{ TAINT_FIRMWARE_WORKAROUND,	'I', ' ' },
 	{ TAINT_OOT_MODULE,		'O', ' ' },
-	{ TAINT_UNSIGNED_MODULE,	'X', ' ' },
+	{ TAINT_UNSIGNED_MODULE,	'E', ' ' },
 };
 
 /**
@@ -229,7 +229,7 @@ static const struct tnt tnts[] = {
  *  'C' - modules from drivers/staging are loaded.
  *  'I' - Working around severe firmware bug.
  *  'O' - Out-of-tree module has been loaded.
- *  'X' - Unsigned module has been loaded.
+ *  'E' - Unsigned module has been loaded.
  *
  *	The string is overwritten by the next call to print_tainted().
  */