feat(plat/arm): Introduce TC1 platform

This renames tc0 platform folder and files to tc, and introduces
TARGET_PLATFORM variable to account for the differences between
TC0 and TC1.
Signed-off-by: Usama Arif <usama.arif@arm.com>
Change-Id: I5b4a83f3453afd12542267091b3edab4c139c5cd

plat/arm/board/tc0/include/tc0_plat.h

-/*
- * Copyright (c) 2020, ARM Limited and Contributors. All rights reserved.
- *
- * SPDX-License-Identifier: BSD-3-Clause
- */
-
-#ifndef tc0_bl31_common_platform_setup_PLAT_H
-#define tc0_bl31_common_platform_setup_PLAT_H
-
-void tc0_bl31_common_platform_setup(void);
-
-#endif /* tc0_bl31_common_platform_setup_PLAT_H */