spl: Correct SPL_SIZE_LIMIT Kconfig option

When introduced this limit was an int but was then changed to hex
without noting as much in the prompt nor changing existing users.  Put
this back to an int.
Reported-by: NFabio Estevam <festevam@gmail.com>
Tested-by: NFabio Estevam <festevam@gmail.com>
Fixes: 2577015d ("spl: add overall SPL size check")
Signed-off-by: NTom Rini <trini@konsulko.com>

common/spl/Kconfig

@@ -26,7 +26,7 @@ config SPL_FRAMEWORK
 	  and the Linux Kernel.  If unsure, say Y.
 
 config SPL_SIZE_LIMIT
-	hex "Maximum size of SPL image"
+	int "Maximum size of SPL image"
 	depends on SPL
 	default 0
 	help