board: sifive: compile stuff only related to SPL in SPL build

As (3581811dc26f "riscv: sifive/fu540: Move SPL related functions to spl.c"),
we put the SPL stuff in spl.c, we don't need to compile unleashed.c and
unmatched.c in SPL build.

Signed-off-by: Zong Li <zong.li@sifive.com>
Reviewed-by: Leo Yu-Chi Liang <ycliang@andestech.com>

board: sifive: unmatched: add initial support for a platform ID EEPROM

Add initial support for the PCB description EEPROM for SiFive HiFive
Unmatched boards.

This implementation is refactored based on Paul Walmsley's porting and
adopt the suggestions from David Abdurachmanov.

Signed-off-by: Paul Walmsley <paul.walmsley@sifive.com>
Signed-off-by: David Abdurachmanov <david.abdurachmanov@sifive.com>
Signed-off-by: Zong Li <zong.li@sifive.com>
Reviewed-by: Leo Yu-Chi Liang <ycliang@andestech.com>

board: sifive: add HiFive Unmatched board support

Add defconfig and board support for HiFive Unmatched.

Signed-off-by: Green Wan <green.wan@sifive.com>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Rick Chen <rick@andestech.com>

board: sifive: unmatched: add initial support for a platform ID EEPROM

Add initial support for the PCB description EEPROM for SiFive HiFive
Unmatched boards.

This implementation is refactored based on Paul Walmsley's porting and
adopt the suggestions from David Abdurachmanov.

Signed-off-by: Paul Walmsley <paul.walmsley@sifive.com>
Signed-off-by: David Abdurachmanov <david.abdurachmanov@sifive.com>
Signed-off-by: Zong Li <zong.li@sifive.com>
Reviewed-by: Leo Yu-Chi Liang <ycliang@andestech.com>

board: sifive: add HiFive Unmatched board support

Add defconfig and board support for HiFive Unmatched.

Signed-off-by: Green Wan <green.wan@sifive.com>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Rick Chen <rick@andestech.com>

board: sifive: add HiFive Unmatched board support

Add defconfig and board support for HiFive Unmatched.

Signed-off-by: Green Wan <green.wan@sifive.com>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Rick Chen <rick@andestech.com>