bootstage: Change CONFIG_BOOTSTAGE_USER_COUNT to an int

There is no good read to make this hex, and integer is more natural for
this type of setting. Update it.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/common/Kconfig b/common/Kconfig
index 5c39663..3b85bf4 100644
--- a/common/Kconfig
+++ b/common/Kconfig
@@ -38,7 +38,7 @@
 		 30,361,327    445,160  start_kernel
 
 config BOOTSTAGE_USER_COUNT
-	hex "Number of boot ID numbers available for user use"
+	int "Number of boot ID numbers available for user use"
 	default 20
 	help
 	  This is the number of available user bootstage records.