spl: fix TPL_SYS_MALLOC_F description

This config option enables the malloc() pool in TPL not the SPL.  Fix
the description to accurately reflect this.

Fixes: fd8497dae54 (spl: Create proper symbols for enabling the malloc() pool)
Signed-off-by: John Keeping <jkeeping@inmusicbrands.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
diff --git a/Kconfig b/Kconfig
index 7df91d7..00ed1ec 100644
--- a/Kconfig
+++ b/Kconfig
@@ -327,7 +327,7 @@
 	  malloc() region in SDRAM once it is inited.
 
 config TPL_SYS_MALLOC_F
-	bool "Enable malloc() pool in SPL"
+	bool "Enable malloc() pool in TPL"
 	depends on SYS_MALLOC_F && TPL
 	default y if SPL_SYS_MALLOC_F
 	help