bootstd: Correct 'VPL' typo

Correct a 'VPL' typo in the Kconfig.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/boot/Kconfig b/boot/Kconfig
index b89916c..d646369 100644
--- a/boot/Kconfig
+++ b/boot/Kconfig
@@ -385,7 +385,7 @@
 	    as well as the "boot_targets" environment variable
 
 config SPL_BOOTSTD
-	bool "Standard boot support in VPL"
+	bool "Standard boot support in SPL"
 	depends on SPL && SPL_DM && SPL_OF_CONTROL && SPL_BLK
 	default y if VPL
 	help