platform: Rename fdt.c to tinyfdt.c

Libfdt already have fdt.c and fdt.h.
Rename both fdt.* present in openSBI to tinyfdt.*

Signed-off-by: Atish Patra <atish.patra@wdc.com>

platform/common/irqchip/plic.c

@@ -8,7 +8,7 @@
  */
 
 #include <sbi/riscv_io.h>
-#include <plat/fdt.h>
+#include <plat/tinyfdt.h>
 #include <plat/irqchip/plic.h>
 
 #define PLIC_PRIORITY_BASE		0x0

platform/common/objects.mk

@@ -7,4 +7,4 @@
 # SPDX-License-Identifier: BSD-2-Clause
 #
 
-platform-common-objs-y += fdt.o
+platform-common-objs-y += tinyfdt.o