scripts/tools-support-relr.sh: un-quote variables

When the CC variable contains quotes, e.g. when using
ccache (make CC="ccache <compiler>"), this script always
fails, so CONFIG_RELR is never enabled, even when the
toolchain supports this feature. Removing the /dev/null
redirect and invoking the script manually shows the issue:

    $ CC='/usr/bin/ccache clang' ./scripts/tools-support-relr.sh
    ./scripts/tools-support-relr.sh: 7: ./scripts/tools-support-relr.sh: /usr/bin/ccache clang: not found

Fix this by un-quoting the variables.

Before:
    $ make ARCH=arm64 CC='/usr/bin/ccache clang' LD=ld.lld \
        NM=llvm-nm OBJCOPY=llvm-objcopy defconfig
    $ grep RELR .config
    CONFIG_ARCH_HAS_RELR=y

With this change:
    $ make ARCH=arm64 CC='/usr/bin/ccache clang' LD=ld.lld \
        NM=llvm-nm OBJCOPY=llvm-objcopy defconfig
    $ grep RELR .config
    CONFIG_TOOLS_SUPPORT_RELR=y
    CONFIG_ARCH_HAS_RELR=y
    CONFIG_RELR=y

Fixes: 5cf896fb ("arm64: Add support for relocating the kernel with RELR relocations")
Reported-by: Dmitry Golovin <dima@golovin.in>
Reviewed-by: Nathan Chancellor <natechancellor@gmail.com>
Reviewed-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Link: https://github.com/ClangBuiltLinux/linux/issues/769


Cc: Peter Collingbourne <pcc@google.com>
Signed-off-by: Ilie Halip <ilie.halip@gmail.com>
Signed-off-by: Will Deacon <will@kernel.org>