lorax: efi: improve using ESP for 'root' device

Simply do nothing, instead of searching by filesystem label. This should
work even if there are multiple devices with the same label.

lorax-templates-qubes/templates/config_files/x86/grub2-efi.cfg

@@ -16,22 +16,19 @@ insmod ext2
 insmod chain
 
 set timeout=5
-### END /etc/grub.d/00_header ###
 
-search --no-floppy --set=root -l '@ISOLABEL@'
+# do not use search for ISO here, 'root' must point ESP, not the whole ISO9660
+# fs, otherwise xen.efi would not be able to access kernel and initrd
 
 menuentry 'Test media and install @PRODUCT@ @VERSION@' --class qubes --class gnu-linux --class gnu --class os {
-    search --no-floppy --set=root -l 'ANACONDA'
     chainloader @EFIDIR@/xen.efi placeholder qubes-check
 }
 
 menuentry 'Install @PRODUCT@ @VERSION@' --class qubes --class gnu-linux --class gnu --class os {
-    search --no-floppy --set=root -l 'ANACONDA'
     chainloader @EFIDIR@/xen.efi
 }
 
 menuentry 'Rescue a @PRODUCT@ system' --class qubes --class gnu-linux --class gnu --class os {
-    search --no-floppy --set=root -l 'ANACONDA'
     chainloader @EFIDIR@/xen.efi placeholder qubes-rescue
 }