kconfig: binman: Check for SPL instead of XPL

Now that SPL means SPL (only) and is not defined for other phases,
update kconfig rules.

This is done in one patch since otherwise many Binman tests fail.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/include/linux/kconfig.h b/include/linux/kconfig.h
index a59f2a6..ec9584b 100644
--- a/include/linux/kconfig.h
+++ b/include/linux/kconfig.h
@@ -40,7 +40,7 @@
 #define _CONFIG_PREFIX TPL_
 #elif defined(CONFIG_VPL_BUILD)
 #define _CONFIG_PREFIX VPL_
-#elif defined(CONFIG_XPL_BUILD)
+#elif defined(CONFIG_SPL_BUILD)
 #define _CONFIG_PREFIX SPL_
 #else
 #define _CONFIG_PREFIX
@@ -54,7 +54,7 @@
  * CONFIG_VAL(FOO) evaluates to the value of
  *  CONFIG_TOOLS_FOO if USE_HOSTCC is defined,
  *  CONFIG_FOO if CONFIG_XPL_BUILD is undefined,
- *  CONFIG_SPL_FOO if CONFIG_XPL_BUILD is defined.
+ *  CONFIG_SPL_FOO if CONFIG_SPL_BUILD is defined.
  *  CONFIG_TPL_FOO if CONFIG_TPL_BUILD is defined.
  *  CONFIG_VPL_FOO if CONFIG_VPL_BUILD is defined.
  */
@@ -107,21 +107,21 @@
  * CONFIG_IS_ENABLED(FOO) expands to
  *  1 if USE_HOSTCC is defined and CONFIG_TOOLS_FOO is set to 'y',
  *  1 if CONFIG_XPL_BUILD is undefined and CONFIG_FOO is set to 'y',
- *  1 if CONFIG_XPL_BUILD is defined and CONFIG_SPL_FOO is set to 'y',
+ *  1 if CONFIG_SPL_BUILD is defined and CONFIG_SPL_FOO is set to 'y',
  *  1 if CONFIG_TPL_BUILD is defined and CONFIG_TPL_FOO is set to 'y',
  *  0 otherwise.
  *
  * CONFIG_IS_ENABLED(FOO, (abc)) expands to
  *  abc if USE_HOSTCC is defined and CONFIG_TOOLS_FOO is set to 'y',
  *  abc if CONFIG_XPL_BUILD is undefined and CONFIG_FOO is set to 'y',
- *  abc if CONFIG_XPL_BUILD is defined and CONFIG_SPL_FOO is set to 'y',
+ *  abc if CONFIG_SPL_BUILD is defined and CONFIG_SPL_FOO is set to 'y',
  *  abc if CONFIG_TPL_BUILD is defined and CONFIG_TPL_FOO is set to 'y',
  *  nothing otherwise.
  *
  * CONFIG_IS_ENABLED(FOO, (abc), (def)) expands to
  *  abc if USE_HOSTCC is defined and CONFIG_TOOLS_FOO is set to 'y',
  *  abc if CONFIG_XPL_BUILD is undefined and CONFIG_FOO is set to 'y',
- *  abc if CONFIG_XPL_BUILD is defined and CONFIG_SPL_FOO is set to 'y',
+ *  abc if CONFIG_SPL_BUILD is defined and CONFIG_SPL_FOO is set to 'y',
  *  abc if CONFIG_TPL_BUILD is defined and CONFIG_TPL_FOO is set to 'y',
  *  def otherwise.
  *