fb_ddc: Allow I2C adapters without SCL read capability

i2c-algo-bit allows I2C adapters without SCL read capability to work
but fb_ddc_read fails to work on them.

Fix fb_ddc_read to work with I2C adapters not capable of reading SCL.

Signed-off-by: Ondrej Zary <linux@rainbow-software.org>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>