luci-app-ddns: fix typo for has_curlssl()

Fixes the incorrect message "HTTPS not supported please disable !" when curl with https support is present.
grep returns exit code 0 when a match is found.

This cherry-picks commit 199d4b1d5c

Signed-off-by: Leong Hui Wong <wong.leonghui@gmail.com>
Signed-off-by: Chuck <fanck0605@qq.com>

applications/luci-app-ddns/luasrc/tools/ddns.lua

@@ -21,7 +21,7 @@ function env_info(type)
 		end
 
 		local function has_curlssl()
-			return (SYS.call( [[$(which curl) -V 2>&1 | grep "Protocols:" | grep -qF "https"]] ) ~= 0)
+			return (SYS.call( [[$(which curl) -V 2>&1 | grep "Protocols:" | grep -qF "https"]] ) == 0)
 		end
 
 		local function has_fetch()