i2c: Let drivers constify i2c_algorithm data

Let drivers constify I2C algorithm method operations tables,
moving them from ".data" to ".rodata".
Signed-off-by: NDavid Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: NJean Delvare <khali@linux-fr.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>