rescue-image: Set explicit wget timeout

Specify explicitly that wget should timeout after three seconds and we
will go for another retry. Failing faster and retrying sooner.

hardware/rescue-image/files/helpers.sh

@@ -107,9 +107,9 @@ download_medkit() {
     mkdir -p /mnt/src
     # Download medkit and signature
     for ext in tar.gz tar.gz.sig; do
-        i=0
+        local i=0
         # We are checking signature, so we don't care about https certificate
-        while ! wget --no-check-certificate -O /mnt/src/medkit.$ext https://repo.turris.cz/hbs/medkit/${BOARD}-medkit${MDKT_VARIANT}-latest.$ext; do
+        while ! wget -T 3 --no-check-certificate -O /mnt/src/medkit.$ext https://repo.turris.cz/hbs/medkit/${BOARD}-medkit${MDKT_VARIANT}-latest.$ext; do
             echo "Can't download $BOARD-medkit-latest.$ext :-("
             sleep 2
             i="$(expr "$i" + 1)"