ti-st: Fix complete_all() wrong usage

complete_all() should only be called once, doing it twice is a clear bug.

8565adbc ("drivers/misc/ti-st: fix read fw version cmd") added the
additional complete_all() call. Since we call complete_all() when
leaving the function we can drop the complete_all() call inside
true branch of the if statement.

Signed-off-by: Daniel Wagner <daniel.wagner@bmw-carit.de>
Cc: Pavan Savoy <pavan_savoy@ti.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>