arch/csky/abiv2/inc/abi/fpu.h with a series of the non-existing config "OPEN_FPU_xxx"

[sunying]

In the header file arch/csky/abiv2/inc/abi/fpu.h, lines 30-64 refer to
 a series of configuration options starting with "OPEN_FPU" for conditional compilation,
 but these configuration options are not defined in any kconfig files,
 which means the "#ifdef CONFIG_OPEN_FPU_xxx" condition contains dead code.

Do these configuration options need to be retained and added later? Or can we simply drop the dead code?


Best regards,
Yanjie Ren
Ying Sun