refactor(qemu): update configuring mbedtls support

Pull in MbedTLS support for sha512 when greater than sha256 is required
based on refactoring for hash algorithm selection for Measured Boot.

Signed-off-by: Lauren Wehrmeister <lauren.wehrmeister@arm.com>
Change-Id: Ib0ca5ecdee7906b41a0e1060339d43ce7a018d31
diff --git a/plat/qemu/qemu/platform.mk b/plat/qemu/qemu/platform.mk
index 6a877c3..8e7f7c8 100644
--- a/plat/qemu/qemu/platform.mk
+++ b/plat/qemu/qemu/platform.mk
@@ -104,6 +104,10 @@
     $(info Including ${MEASURED_BOOT_MK})
     include ${MEASURED_BOOT_MK}
 
+    ifneq (${MBOOT_EL_HASH_ALG}, sha256)
+        $(eval $(call add_define,TF_MBEDTLS_MBOOT_USE_SHA512))
+    endif
+
     BL2_SOURCES		+=	plat/qemu/qemu/qemu_measured_boot.c	\
 				plat/qemu/qemu/qemu_common_measured_boot.c	\
 				plat/qemu/qemu/qemu_helpers.c		\