test: work around for EFI terminal size probing

When the UEFI sub-system is initialized it sends an escape sequence to the
serial console to determine the terminal size. This stops the
run_command_list() function of the console emulation from recognizing the
U-Boot command line prompt.

Add a 'print -e' command as first command in the command list to work
around this issue.

Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>