nds32: fix build error "relocation truncated to fit: R_NDS32_25_PCREL_RELA" when

make allyesconfig

It will cause a linking error because the jump assembly code were using j,
however it may be not enough to jump to the destination. We have to change it
with pseudo instruction b. In that way, assembler will generate a set of safe
assembly codes to make sure the destination is able to jump.

Toolchain:
https://mirrors.edge.kernel.org/pub/tools/crosstool/files/bin/x86_64/8.1.0/x86_64-gcc-8.1.0-nolibc-nds32le-linux.tar.gz

Command:
PATH=/NOBACKUP/atcsqa06/greentime/os/toolchain-kernel.org/gcc-8.1.0-nolibc/nds32le-linux/bin:$PATH ARCH=nds32 CROSS_COMPILE=nds32le-linux- make allyesconfig
PATH=/NOBACKUP/atcsqa06/greentime/os/toolchain-kernel.org/gcc-8.1.0-nolibc/nds32le-linux/bin:$PATH ARCH=nds32 CROSS_COMPILE=nds32le-linux- make -j8

  MODPOST vmlinux.o
WARNING: EXPORT symbol "copy_page" [vmlinux] version generation failed, symbol will not be versioned.
WARNING: EXPORT symbol "clear_page" [vmlinux] version generation failed, symbol will not be versioned.
nds32le-linux-ld: kernel/futex.o:(.fixup+0x4): relocation truncated to fit: R_NDS32_25_PCREL_RELA against `.text'
nds32le-linux-ld: kernel/futex.o:(.fixup+0xaa): relocation truncated to fit: R_NDS32_25_PCREL_RELA against `.text'
nds32le-linux-ld: kernel/futex.o:(.fixup+0xb0): relocation truncated to fit: R_NDS32_25_PCREL_RELA against `.text'
nds32le-linux-ld: kernel/futex.o:(.fixup+0xb6): relocation truncated to fit: R_NDS32_25_PCREL_RELA against `.text'
nds32le-linux-ld: kernel/futex.o:(.fixup+0xbc): relocation truncated to fit: R_NDS32_25_PCREL_RELA against `.text'
nds32le-linux-ld: kernel/futex.o:(.fixup+0xc4): relocation truncated to fit: R_NDS32_25_PCREL_RELA against `.text'
Makefile:1010: recipe for target 'vmlinux' failed
make: *** [vmlinux] Error 1

Signed-off-by: Greentime Hu <greentime@andestech.com>