local.conf.sample.extended: remove RM_OLD_IMAGE

RM_OLD_IMAGE has been removed so don't include this variable in
sample local.conf

(From meta-yocto rev: 0a881d01ab2b0a3f721323447b4c970ab3fd4755)

Signed-off-by: Joshua Lock <joshua.g.lock@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta-poky/conf/local.conf.sample.extended

@@ -265,9 +265,6 @@
 #COPYLEFT_RECIPE_TYPES = 'target'
 #
 
-# Remove the old image before the new one generated to save disk space
-#RM_OLD_IMAGE = "1"
-
 #
 # GCC/LD FLAGS to enable more secure code generation
 #