C-SKY: Make dynamic linker's name compitable with the older gcc.

C-SKY: Make dynamic linker's name compitable with the older gcc.

__CSKY_HARD_FLOAT_ABI__ was added on gcc 11 to specify whether
-mfloat-abi=hard is set.  On older gcc, the float ABI is defined
solely with __CSKY_HARD_FLOAT__.  If __CSKY_HARD_FLOAT__ is set, it can
be either a hard-float ABI (gcc older than 11, or gcc11 -mfloat-abi=hard
(__CSKY_HARD_FLOAT_ABI__ is set) or -mfloat-abi=softfp
(__CSKY_HARD_FLOAT_ABI__ is not set). To be compatible with older gcc,
use __CSKY_HARD_FLOAT_FPU_SF__ identify if -mfloat-abi is supported,
because it is added to gcc at the same time as -mfloat-abi.

Reviewed-by: Mao Han  <han_mao@linux.alibaba.com>
Reviewed-by: Adhemerval Zanella  <adhemerval.zanella@linaro.org>