vendor.sh: remove unnecessary check

mktemp will never return empty output, and the next
command after it is an mkdir, which would throw an
error anyway, if the string is empty.

Signed-off-by: Leah Rowe <leah@libreboot.org>

include/vendor.sh

@@ -129,7 +129,6 @@ extract_intel_me()
 	e "$_me" f && return 0
 
 	sdir="$(mktemp -d)"
-	[ -z "$sdir" ] && return 0
 	mkdir -p "$sdir" || $err "extract_intel_me: !mkdir -p \"$sdir\""
 
 	set +u +e