fbdev: panel-tpo-td043mtea1: Convert sprintf() to sysfs_emit()

Per filesystems/sysfs.rst, show() should only use sysfs_emit()
or sysfs_emit_at() when formatting the value to be returned to user space.

coccinelle complains that there are still a couple of functions that use
snprintf(). Convert them to sysfs_emit().

CC: Helge Deller <deller@gmx.de>
CC: linux-omap@vger.kernel.org
CC: linux-fbdev@vger.kernel.org
CC: dri-devel@lists.freedesktop.org
Signed-off-by: Li Zhijian <lizhijian@fujitsu.com>
Signed-off-by: Helge Deller <deller@gmx.de>