hikey, hikey960: set CFG_TEE_RAM_VA_SIZE to 2 MiB

Commit 8fd4d26 ("plat-hikey: support generic RAM layout") has
inadvertently removed the platform-specific definition of
TEE_RAM_VA_SIZE for HiKey platforms. It was 2 MiB before, and became
1 MiB (the default). This commit restores the proper value.

Fixes the following panic on boot (HiKey960, 32-bit TEE core with pager
enabled):

 I/TC: Pager is enabled. Hashes: 1824 bytes
 I/TC: Pager pool size: 252kB
 I/TC: OP-TEE version: 3.6.0-182-g2d7a8964df-dev (gcc version 6.2.1 20161016 (Linaro GCC 6.2-2016.11)) #5 Mon 07 Oct 2019 08:22:21 AM UTC arm
 E/TC:0 0 Panic at core/lib/libtomcrypt/mpi_desc.c:39 <get_mp_scratch_memory_pool>
 E/TC:0 0 Call stack:
 E/TC:0 0  0x3f003a4d

Fixes: 8fd4d26 ("plat-hikey: support generic RAM layout")
Signed-off-by: Jerome Forissier <jerome@forissier.org>

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

@@ -62,5 +62,6 @@ CFG_TZDRAM_START ?= 0x3F000000
 CFG_TZDRAM_SIZE ?= 0x01000000
 CFG_SHMEM_START ?= 0x3EE00000
 CFG_SHMEM_SIZE ?= 0x00200000
+CFG_TEE_RAM_VA_SIZE ?= 0x00200000
 
 CFG_IN_TREE_EARLY_TAS += avb/023f8f1a-292a-432b-8fc4-de8471358067