fpga/fw: Resize ROM and FW_RAM, add RESETINFO partition

In order to be able to leave data for firmware signalling the
intention with a reset or to leave data for the next app in a chain of
apps, we introduce a part of FW_RAM that can be used to store this
data. In order to do this, we:

- Change size of ROM from 6 KB to 8 KB.
- Change size of FW_RAM, from 2 KB to 4 KB.
- Add RESETINFO memory partition inside FW_RAM.
- Add generation of map file.
- Change CFLAGS from using -O2 to using -Os.
- Update address ranges for valid access to ROM and FW_RAM.
- Move stack to be located before data+bss and the RESETINFO data
  above them. This also means we introduce hardware stack overflow
  protection through the Security Monitor.
- Revise firmware README to the new use of FW_RAM.

hw/application_fpga/fw/tk1/main.c

@@ -334,8 +334,8 @@ static void run(const struct context *ctx)
 	// clang-format off
 #ifndef S_SPLINT_S
 	asm volatile(
-		"li a0, 0xd0000000;" // FW_RAM
-		"li a1, 0xd0000800;" // End of 2 KB FW_RAM (just past the end)
+		"la a0, _sstack;"
+		"la a1, _estack;"
 		"loop:;"
 		"sw zero, 0(a0);"
 		"addi a0, a0, 4;"