nvmem: set nvmem->owner to nvmem->dev->driver->owner if unset

All nvmem drivers are supposed to set the owner field of struct
nvmem_config, but this matches nvmem->dev->driver->owner.

As far as I see in drivers/nvmem/ directory, all the drivers are
the case.  So, make nvmem_register() set the nvmem's owner to the
associated driver's owner unless nvmem_config sets otherwise.

Remove .owner settings in the drivers that are now redundant.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>