test/py: efi_secboot: remove unused function

'tool_is_in_path' function is no longer used anywhere after Heinrich
has removed 'sudo' version of fixture setup.

Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>
Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
1 file changed