riscv: disable HAVE_LD_DEAD_CODE_DATA_ELIMINATION for LLD

Linking allyesconfig with ld.lld-17 with CONFIG_DEAD_CODE_ELIMINATION=y
takes hours.  Assuming this is a performance regression that can be
fixed, tentatively disable this for now so that allyesconfig builds
don't start timing out.  If and when there's a fix to ld.lld, this can
be converted to a version check instead so that users of older but still
supported versions of ld.lld don't hurt themselves by enabling
CONFIG_LD_DEAD_CODE_DATA_ELIMINATION=y.

Link: https://github.com/ClangBuiltLinux/linux/issues/1881
Link: https://lore.kernel.org/linux-riscv/ZJXTwqZIkXLxXaSi@google.com/Reported-by: Palmer Dabbelt <palmer@dabbelt.com>
Suggested-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>

arch/riscv/Kconfig

@@ -115,7 +115,8 @@ config RISCV
 	select HAVE_KPROBES if !XIP_KERNEL
 	select HAVE_KPROBES_ON_FTRACE if !XIP_KERNEL
 	select HAVE_KRETPROBES if !XIP_KERNEL
-	select HAVE_LD_DEAD_CODE_DATA_ELIMINATION
+	# https://github.com/ClangBuiltLinux/linux/issues/1881
+	select HAVE_LD_DEAD_CODE_DATA_ELIMINATION if !LD_IS_LLD
 	select HAVE_MOVE_PMD
 	select HAVE_MOVE_PUD
 	select HAVE_PCI