tests: kernel: fpu_sharing: Enable it on VFP platfrom of aarch32

- Remove raising compilation error in `float_regs_arm_gcc.h`
    These macros are checked in 'load_store.c', so no need to check them
    again in 'float_regs_arm_gcc.h'

- Enable this test on the VFP platform of aarch32

Signed-off-by: Huifeng Zhang <Huifeng.Zhang@arm.com>