Avoid name collision with user_fpsimd_state in <asm/ptrace.h>.

We don't want to use <asm/ptrace.h> because (a) it'll drag in a bunch of
namespace pollution and (b) the registers should be "long double" for
userspace, not the kernel's uint128s. So just use a slightly different
name for our struct (which matches the traditional names for these structs
anyway).

Bug: http://b/21695943
Bug: https://code.google.com/p/android/issues/detail?id=86712
Change-Id: I8812ca98cfe6b649dbd31f7d6aea41928ba2acbd