fix(iso): Find zfs partition on legacy BIOS machine (#7)

setup.sh

@@ -194,11 +194,15 @@ function select_part () {
     part_type="${1:?}" # 'boot' or 'zfs'
     zfs_install_drive="${2:-}"
 
+    if [[ "${part_type}" = 'boot' ]]; then
         if [[ "${part_schema}" = 'mbr' ]]; then
             specific_part_type='boot'
         else
             specific_part_type='efi'
         fi
+    else
+        specific_part_type="${part_type}"
+    fi
 
     if [[ "${zfs_install_drive}" ]]; then
         # This is intended to find correct boot/EFI partition