opensbi: Do not enforce objcopy from binutils for clang

This has adverse effect now with clang-21 on riscv64 qemu
where opensbi ends up not being found during boot and qemu
getting stuck in early boot.

Signed-off-by: Khem Raj <raj.khem@gmail.com>

Author: kraj

conf/nonclangable.conf

@@ -378,7 +378,6 @@ OBJCOPY:pn-linux-linaro-qcomlt:toolchain-clang = "${HOST_PREFIX}objcopy"
 OBJCOPY:pn-linux-intel:toolchain-clang = "${HOST_PREFIX}objcopy"
 
 # see https://github.com/llvm/llvm-project/issues/53948
-OBJCOPY:pn-opensbi:toolchain-clang = "${HOST_PREFIX}objcopy"
 OBJCOPY:pn-libc-bench:toolchain-clang = "${HOST_PREFIX}objcopy"
 STRIP:pn-libc-bench:toolchain-clang = "${HOST_PREFIX}strip"
 OBJCOPY:pn-aufs-util:toolchain-clang = "${HOST_PREFIX}objcopy"