lint: sh: enable previously disabled warnings

The only warnings that remain disabled globally for now handle the
differences between POSIX sh and Busybox ash, as support for the latter
was only added in shellcheck 0.10.

scripts/lint-sh.sh

@@ -17,7 +17,7 @@ find package -type f | while read -r file; do
 	is_scriptfile "$file" || continue
 
 	echo "Checking $file"
-	shellcheck -f gcc -x -s sh -e SC2039,SC1091,SC2155,SC2034,SC3043,SC3037,SC3057 "$file"
+	shellcheck -f gcc -x -s sh -e SC2039,SC3043,SC3037,SC3057 "$file"
 done
 
 find scripts -type f | while read -r file; do