riscv: Require FRAME_POINTER for some configurations

Some V configurations implicitly turn on '-fno-omit-frame-pointer',
but leaving FRAME_POINTER disabled. This makes it hard to reason about
the FRAME_POINTER config, and also triggers build failures introduced
in by the commit in the Fixes: tag.

Select FRAME_POINTER explicitly for these configurations.

Fixes: ebc9cb03 ("riscv: stack: Fixup independent softirq stack for CONFIG_FRAME_POINTER=n")
Signed-off-by: Björn Töpel <bjorn@rivosinc.com>
Tested-by: Randy Dunlap <rdunlap@infradead.org>
Acked-by: Randy Dunlap <rdunlap@infradead.org>
Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
Link: https://lore.kernel.org/r/20230823082845.354839-1-bjorn@kernel.org


Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>