Makefile: Drop -rc6

When tagging and releasing v2023.07 I forgot to drop the -rc6 tag. For
regular use, I've made a v2023.07.01 tag, but for here we can just drop
the -rc6 tag.

Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/Makefile b/Makefile
index 8d9aef4..1d551da 100644
--- a/Makefile
+++ b/Makefile
@@ -3,7 +3,7 @@
 VERSION = 2023
 PATCHLEVEL = 07
 SUBLEVEL =
-EXTRAVERSION = -rc6
+EXTRAVERSION =
 NAME =
 
 # *DOCUMENTATION*