feat(msm8916): initial platform port

Introduce the bare mimimum base of the msm8916 BL31 port. This is
pretty much just a standard platform "skeleton" with CPU/memory
initialization and an UART driver. This allows booting into
e.g. U-Boot with working UART output.

Note that the plat/qti/msm8916 port is completely separate and does not
make use of anything in plat/qti/common at the moment. The main reason
for that is that plat/qti/common is heavily focused around having a
binary "qtiseclib" component, while the MSM8916 port is fully
open-source (and therefore somewhat limited to publicly documented
functionality).

In the future it might be possible to re-use some of the open-source
parts in plat/qti/common (e.g. spmi_arb.c or pm_ps_hold.c) but it's
not strictly required for the basic functionality supported so far.

Change-Id: I7b4375df0f947b3bd1e55b0b52b21edb6e6d175b
Signed-off-by: Stephan Gerhold <stephan@gerhold.net>
diff --git a/plat/qti/msm8916/include/uartdm_console.h b/plat/qti/msm8916/include/uartdm_console.h
new file mode 100644
index 0000000..0f09ba8
--- /dev/null
+++ b/plat/qti/msm8916/include/uartdm_console.h
@@ -0,0 +1,12 @@
+/*
+ * Copyright (c) 2021, Stephan Gerhold <stephan@gerhold.net>
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#ifndef UARTDM_CONSOLE_H
+#define UARTDM_CONSOLE_H
+
+int console_uartdm_register(console_t *console, uintptr_t base_addr);
+
+#endif /* UARTDM_CONSOLE_H */