ARM: dts: n9, n950: Remove nokia,nvm-size property

Remove nokia,nvm-size property as it is no longer needed. The driver can
nowadays figure out the size so do not specify it in DT.

Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>