pkgbase: Remove /boot/firmware from bootloader package

For now we don't ship anything in /boot/firmware, but some up coming commit
will ship wifi drivers in it and we want them to be in their own package.

Sponsored by:	Beckhoff Automation GmbH & Co. KG

release/scripts/mtree-to-plist.awk

@@ -43,7 +43,7 @@
 				if ($1 ~ /^\/boot\//) {
 					if (kernel != "" && $1 ~ /^\/boot\/dtb\//)
 						pkgname="dtb"
-					else
+					else if ($1 !~ /^\/boot\/firmware\//)
 						pkgname="bootloader"
 				}
 				gsub(/package=/, "", pkgname)