video: ssd1307fb: Add support for SSD1306 OLED controller

The Solomon SSD1306 OLED controller is very similar to the SSD1307,
except for the fact that the power is given through an external PWM for
the 1307, and while the 1306 can generate its own power without any PWM.

Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>