x86/um/vdso: Drop unnecessary cc-ldoption

x86/um/vdso: Drop unnecessary cc-ldoption

Towards the goal of removing cc-ldoption, it seems that --hash-style=
was added to binutils 2.17.50.0.2 in 2006. The minimal required version
of binutils for the kernel according to
Documentation/process/changes.rst is 2.20.

Suggested-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: Nick Desaulniers <ndesaulniers@google.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: anton.ivanov@cambridgegreys.com
Cc: clang-built-linux@googlegroups.com
Cc: jdike@addtoit.com
Cc: linux-um@lists.infradead.org
Cc: richard@nod.at
Link: http://lkml.kernel.org/r/20190423211554.1594-1-ndesaulniers@google.com
Link: https://gcc.gnu.org/ml/gcc/2007-01/msg01141.html
Signed-off-by: Ingo Molnar <mingo@kernel.org>