Fix build.sh usage function (#1368)

## Description

Usage function not defined before use params are not properly specified

## Type of change

<!--- Please check the type of change your PR introduces: --->
- [ ] 🌻 Feature
- [x] 🐛 Bugfix
- [ ] 🗺️ Documentation
- [ ] 🤖 Test
- [ ] 💻 CI/Deployment
- [x] 🐹 Trivial/Minor

## Issue(s)

## Test Plan

<!-- How will this be tested prior to merging.-->
- [x] 💪 Manual
- [ ] ⚡ Unit test
- [ ] 💚 E2E

build/build.sh

@@ -2,6 +2,15 @@
 
 set -e
 
+usage() {
+        echo "Usage: $(basename $0) binary | image [--platforms ...] [--tag ...]"
+        echo ""
+        echo "OPTIONS"
+        echo " -p | --platforms  Platforms to build for (default: $PLATFORMS)"
+        echo "                 Specify multiple platforms using ',' (eg: linux/amd64,darwin/arm)"
+        echo " -t | --tag        Tag for container image (default: $TAG)"
+}
+
 ROOT=$(dirname $(dirname $(readlink -f $0)))
 GOVER=1.18                           # go version
 CORSO_BUILD_CACHE="/tmp/.corsobuild" # shared persistent cache
@@ -44,15 +53,6 @@ while [ "$#" -gt 0 ]; do
 	shift
 done
 
-usage() {
-	echo "Usage: $(basename $0) binary | image [--platforms ...] [--tag ...]"
-	echo ""
-	echo "OPTIONS"
-	echo " -p | --platforms  Platforms to build for (default: $PLATFORMS)"
-	echo "                 Specify multiple platforms using ',' (eg: linux/amd64,darwin/arm)"
-	echo " -t | --tag        Tag for container image (default: $TAG)"
-}
-
 if [ "$MODE" == "binary" ]; then
 	mkdir -p ${CORSO_BUILD_CACHE} # prep env
 	for platform in ${PLATFORMS/,/ }; do