Revert "x86: Force asm-goto"

This reverts commit e501ce95.

This change broke building the x86_64 kernel with clang. The kernel
still builds and works fine without asm-goto support. Revert this
change to unblock testing clang kernels on cuttlefish.

Bug: 120440614
Change-Id: Ib32498acc0596264f8cd15de0b603579dd643dd7
Signed-off-by: Alistair Strachan <astrachan@google.com>