staging: fbtft: remove redundant initialization of txbuf16

txbuf16 is being initialized at declaration time and then later
set to another value without it being read inbetween, hence making
the initialization redundant.  Fix this by setting txbuf16 just
the once. Also clean up some incorrect indentations. Cleans up
clang build warning:

warning: Value stored to 'txbuf16' during its initialization is never read

Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>