media: dt-bindings: smia: Remove documentation of nokia,nvm-size

The nokia,nvm-size property was used to tell the size of the NVM memory
accessible through the sensor's register interface. However, while the
size isn't directly readable through the sensor's register interface, it
can be detected reading the NVM memory until the selected page is no
longer available.

Thus remove this property.

Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>