refactor(measured-boot): update event log hash alg

Updating the TPM_HASH_ALG to reflect the new name for the Event Log hash
algorithm MBOOT_EL_HASH_ALG.

Signed-off-by: Lauren Wehrmeister <lauren.wehrmeister@arm.com>
Change-Id: Ib28fced3065917fb46f7ed155f6512cf364cc281
diff --git a/tf_config/qemu-mb_hash256 b/tf_config/qemu-mb_hash256
index 5145502..6b48c8e 100644
--- a/tf_config/qemu-mb_hash256
+++ b/tf_config/qemu-mb_hash256
@@ -1,4 +1,4 @@
 CROSS_COMPILE=aarch64-none-elf-
 MEASURED_BOOT=1
 PLAT=qemu
-TPM_HASH_ALG=sha256
+MBOOT_EL_HASH_ALG=sha256