Revert "ARM: 9444/1: add KEEP() keyword to ARM_VECTORS"

This reverts commit 9f7ae45f which is
commit c3d944a3 upstream.

It breaks the Android kernel build for the ARM target, and can be
brought back in the future in an safe way if it is really needed.

Bug: 161946584
Change-Id: I9e4bffade9793ac8f2a12f4b9f3fc5f9344f2649
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>