MIPS: Probe toolchain support of -msym32

[ Upstream commit 18ca63a2e23c5e170d2d7552b64b1f5ad019cd9b ]

msym32 is not supported by LLVM toolchain.
Workaround by probe toolchain support of msym32 for KBUILD_SYM32
feature.

Link: https://github.com/ClangBuiltLinux/linux/issues/1544


Signed-off-by: Jiaxun Yang <jiaxun.yang@flygoat.com>
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Signed-off-by: WangYuli <wangyuli@uniontech.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>