riscv: Set 5.4 as minimum kernel version for riscv32

riscv: Set 5.4 as minimum kernel version for riscv32

5.4 is first stable API as far as rv32 is concerned see [1]

[1] https://sourceware.org/git/?p=glibc.git;a=commit;h=7a55dd3fb6d2c307a002a16776be84310b9c8989

Signed-off-by: Khem Raj <raj.khem@gmail.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Alistair Francis <alistair.francis@wdc.com>
Cc: Bin Meng <bin.meng@windriver.com>
Message-Id: <20211216073111.2890607-1-raj.khem@gmail.com>
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>