Automatically run EFI conversion steps

Before this commit the user was supposed to give the -e cmdline parameter
to run the EFI conversion when necessary. But it was missing in the getopts
parameter list, so it didn't work.

Instead of fixing it, I opted to remove the -e parameter alltogether and
automatically detect if the system is running on EFI or not. Because if the
user should forget to give -e on an EFI system, it would result in an unbootable
system without any bootmanager installed. Fixing this situation takes time and
requires some sysadmin skills, so we should take steps to avoid this situation.

Detecting if the system runs on EFI or not can reliably done by checking for
/sys/firmware/efi/.

migrate2rocky.sh

@@ -382,7 +382,6 @@ usage() {
       "Usage: ${0##*/} [OPTIONS]" \
       '' \
       'Options:' \
-      '-e Update EFI boot sector when done' \
       '-h Display this help' \
       '-r Convert to rocky' \
       '-V Verify switch' \
@@ -517,6 +516,21 @@ EOF
     dnf -y distro-sync || exit_message "Error during distro-sync."
 }
 
+# Check if this system is running on EFI
+# If yes, we'll need to run fix_efi() at the end of the conversion
+efi_check () {
+    # Check if we have /sys mounted and it is looking sane
+    if ! [[ -d /sys/class/block ]]; then
+	exit_message "/sys is not accessible."
+    fi
+    
+    # Now that we know /sys is reliable, use it to check if we are running on EFI or not
+    if [[ -d /sys/firmware/efi/ ]]; then
+	declare -g update_efi
+	update_efi=true
+    fi
+}
+
 # Called to update the EFI boot.
 fix_efi () (
     grub2-mkconfig -o /boot/efi/EFI/rocky/grub.cfg ||
@@ -540,9 +554,6 @@ while getopts "hrVR" option; do
     V)
       verify_all_rpms=true
       ;;
-    e)
-      update_efi=true
-      ;;
     *)
       printf '%s\n' "${errcolor}Invalid switch.$nocolor"
       usage
@@ -553,6 +564,7 @@ if (( ! noopts )); then
     usage
 fi
 
+efi_check
 bin_check
 
 if [[ $verify_all_rpms ]]; then