drivers/staging/speakup: fix indent coding style problem in spk_ttyio.c

This is a patch to the spk_ttyio.c file which fixes up the indent error
reported by the checkpatch.pl tool.
Signed-off-by: NRui Teng <rui.teng@linux.vnet.ibm.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>