plat-k3: disable PRNG by default for all K3

All K3 devices already have PRNG disabled, remove the check and
set this unconditionally.

Signed-off-by: Andrew Davis <afd@ti.com>
Acked-by: Jerome Forissier <jerome.forissier@linaro.org>
Acked-by: Etienne Carriere <etienne.carriere@foss.st.com>

core/arch/arm/plat-k3/conf.mk

@@ -1,6 +1,7 @@
 CFG_WITH_STATS ?= y
 CFG_CRYPTO_WITH_CE ?= y
 CFG_CONSOLE_UART ?= 0
+CFG_WITH_SOFTWARE_PRNG ?= n
 
 CFG_TZDRAM_START ?= 0x9e800000
 CFG_TZDRAM_SIZE ?= 0x01400000 # 20MB
@@ -22,12 +23,6 @@ ifneq (,$(filter ${PLATFORM_FLAVOR},am65x))
 $(call force,CFG_CORE_CLUSTER_SHIFT,1)
 endif
 
-ifneq (,$(filter ${PLATFORM_FLAVOR},am65x j721e j784s4 am64x am62x))
-CFG_WITH_SOFTWARE_PRNG ?= n
-else
-$(call force,CFG_WITH_SOFTWARE_PRNG,y)
-endif
-
 ifneq ($(CFG_WITH_SOFTWARE_PRNG),y)
 $(call force,CFG_SA2UL,y)
 CFG_HWRNG_QUALITY ?= 1024