efi_loader: Clean up tcg2 once in case of failure

efi_init_event_log() calls tcg2_uninit() in case of failure.
We can skip that since the function is called on efi_tcg2_register()
which also cleans up if an error occurs

Signed-off-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>
Reviewed-by: Heinrich Schuchardt <xypron.glpk@gmx.de>