staging: fbtft: Fix line continuation

Fix checkpatch warning: avoid unnecessary line continuation
to allow grepping of whole error message.

Signed-off-by: Matthias Wolf <der_wolf_@web.de>
Signed-off-by: Felix Siegel <felix.siegel@stud.uni-hannover.de>
Signed-off-by: Tim Cofala <cofala@stud.uni-hannover.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>