oem-factory-reset gui-init: fix whiptail_error segfaulting because selfcalling itself; fix typo in gui-init

[tlaurion]

fix bugs introduced by #1698:

• whiptail_error was self calling itself in case no usb security dongle was connected instead of asking the user to plug it in and try again
• whiptail_error and whiptail_warning are overrides of sourced /etc/gui_functions
  • therefore, whiptail_error calling whiptail_error was self calling passing wrong paramters and whiptail prompt was never showed.
  • fixed by renaming oem-factory-reset's whiptail_error into local_whiptail_error function and changing whiptail_error_die and the only place where this fonction was called directly

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Superseeds #1777

Addresses https://github.com/linuxboot/heads/issues/1395#issuecomment-2308014938 : thanks for reporting @arhabd

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No need for review after testing, "emergency" bugfix

[tlaurion]

Tested on qemu and x230. Merging.