devfs: Drop dev_lseek_default() ...

Only the following cdevs do not declare an .lseek() operation:

  - Console devices in common/console.c
  - Firmware framework in common/firmware.c
  - JTAG driver in drivers/misc/jtag.c
  - UBI in drivers/mtd/ubi/barebox.c

Of those four, first two are marked DEVFS_IS_CHARACTER_DEV and
implement only .write() operation and the last two don't implement
anything but .ioctl(). While there's probably no meaningful way to use
lseek() against any of those devices, there doesn't seem to be any
harm in allowing it either.

Change devfs_lseek() to ignore absense of .lseek() callback and drop
dev_lseek_default() and all references to it in the codebase.

Signed-off-by: Andrey Smirnov <andrew.smirnov@gmail.com>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

i2c: introduce device_i2c_driver() macro ...

Add macro and dependency to avoid boilerplate code. Since now simple
i2c drivers only have to include the i2c.h header and call the
device_i2c_driver() macro to register a i2c device driver.

Signed-off-by: Marco Felsch <m.felsch@pengutronix.de>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

rename file_operations -> cdev_operations ...

Linux also has struct file_operations which are something different.
Rename our file_operations to cdev_operations which better matches
what we have.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

mfd: add act8846 driver ...

Signed-off-by: Beniamino Galvani <b.galvani@gmail.com>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>