arch: arm64: force -fno-pic

The aarch64-linux-android- toolchain enables -fpic by default.  -fpic
isn't needed for the kernel and breaks CONFIG_JUMP_LABEL, so turn it
off.

Change-Id: I685da1dc60e4cf1e9abcfb56e03654675ac02a0c
Signed-off-by: Greg Hackmann <ghackmann@google.com>