[nrf noup] Replace XOROSHIRO_RANDOM_GENERATOR

It has been deprecated and the correct one to use now is
XOSHIRO_RANDOM_GENERATOR.

Signed-off-by: Dominik Ermel <dominik.ermel@nordicsemi.no>

config/nrfconnect/chip-module/Kconfig.defaults

@@ -277,7 +277,7 @@ choice OPENTHREAD_SECURITY
 endchoice
 
 choice RNG_GENERATOR_CHOICE
-    default XOROSHIRO_RANDOM_GENERATOR if SOC_SERIES_NRF53X
+    default XOSHIRO_RANDOM_GENERATOR if SOC_SERIES_NRF53X
 endchoice
 
 config OBERON_BACKEND