README: Correct reference for CONFIG_SUPPORT_RAW_INITRD

Signed-off-by: NTom Rini <trini@ti.com>

README

@@ -5063,7 +5063,7 @@ On some platforms, it's possible to boot Linux zImage. This is done
 using the "bootz" command. The syntax of "bootz" command is the same
 as the syntax of "bootm" command.
 
-Note, defining the CONFIG_SUPPORT_INITRD_RAW allows user to supply
+Note, defining the CONFIG_SUPPORT_RAW_INITRD allows user to supply
 kernel with raw initrd images. The syntax is slightly different, the
 address of the initrd must be augmented by it's size, in the following
 format: "<initrd addres>:<initrd size>".