video: ssd1307fb: Improve a size determination in ssd1307fb_probe()

video: ssd1307fb: Improve a size determination in ssd1307fb_probe()

Replace the specification of a data structure by a pointer dereference
as the parameter for the operator "sizeof" to make the corresponding size
determination a bit safer according to the Linux coding style convention.

This issue was detected by using the Coccinelle software.

Signed-off-by: Markus Elfring <elfring@users.sourceforge.net>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Bastian Stender <bst@pengutronix.de>
Cc: Jyri Sarha <jsarha@ti.com>
Cc: Tomi Valkeinen <tomi.valkeinen@ti.com>
Signed-off-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>