media: i2c: add new driver for single string flash. This patch adds the driver for the single string flash products of TI. Several single string flash controllers of TI have similar register map and bit data. This patch enables one driver to support five products, lm3556, lm3561, lm3642 and lm3648. Signed-off-by: Daniel Jeong <gshark.jeong@gmail.com>