plat: imx8mm: Enable Trusted Boot

This patch enables Trusted Boot on the i.MX8MM with BL2 doing image
verification from a FIP prior to hand-over to BL31.
Signed-off-by: Bryan O'Donoghue <bryan.odonoghue@linaro.org>
Signed-off-by: Ying-Chun Liu (PaulLiu) <paulliu@debian.org>
Change-Id: I3c22783a5c49544d0bace8ef3724784b9b7cc64a

plat/imx/imx8m/imx8mm/imx8mm_rotpk.S

+/*
+ * Copyright (c) 2021, ARM Limited and Contributors. All rights reserved.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+	.global imx8mm_rotpk_hash
+	.global imx8mm_rotpk_hash_end
+imx8mm_rotpk_hash:
+	/* DER header */
+	.byte 0x30, 0x31, 0x30, 0x0D, 0x06, 0x09, 0x60, 0x86, 0x48
+	.byte 0x01, 0x65, 0x03, 0x04, 0x02, 0x01, 0x05, 0x00, 0x04, 0x20
+	/* SHA256 */
+	.incbin ROTPK_HASH
+imx8mm_rotpk_hash_end:

plat/imx/imx8m/imx8mm/imx8mm_trusted_boot.c

+/*
+ * Copyright (c) 2021, ARM Limited and Contributors. All rights reserved.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#include <plat/common/platform.h>
+
+extern char imx8mm_rotpk_hash[], imx8mm_rotpk_hash_end[];
+
+int plat_get_rotpk_info(void *cookie, void **key_ptr, unsigned int *key_len,
+			unsigned int *flags)
+{
+	*key_ptr = imx8mm_rotpk_hash;
+	*key_len = imx8mm_rotpk_hash_end - imx8mm_rotpk_hash;
+	*flags = ROTPK_IS_HASH;
+
+	return 0;
+}
+
+int plat_get_nv_ctr(void *cookie, unsigned int *nv_ctr)
+{
+	*nv_ctr = 0;
+
+	return 0;
+}
+
+int plat_set_nv_ctr(void *cookie, unsigned int nv_ctr)
+{
+	return 1;
+}
+
+int plat_get_mbedtls_heap(void **heap_addr, size_t *heap_size)
+{
+	return get_mbedtls_heap_helper(heap_addr, heap_size);
+}