[nrf noup] draft: update MBEDTLS_PSA_CRYPTO_EXTERNAL_RNG deps

This needs to be revisited but the newly added dependency on
the entropy_generator doesn't work with nrf_security.

Signed-off-by: Georgios Vasilakis <[email protected]>

Author: Vge0rge

modules/mbedtls/Kconfig.tls-generic

@@ -524,7 +524,6 @@ choice MBEDTLS_PSA_CRYPTO_RNG_SOURCE
 
 config MBEDTLS_PSA_CRYPTO_EXTERNAL_RNG
 	bool "Use a cryptographically secure driver as random source"
-	select ENTROPY_GENERATOR
 	help
 	  Use a cryptographically secure random generator to provide random data
 	  instead of legacy Mbed TLS modules. This has a smaller footprint