x86/fpu: Call fpu__init_cpu_ctx_switch() from fpu__init_cpu()

x86/fpu: Call fpu__init_cpu_ctx_switch() from fpu__init_cpu()

fpu__init_cpu() is currently called from fpu__init_system(),
which is the wrong place for it: call it from the proper high level
per CPU init function, fpu__init_cpu().

Note, we still keep the old call site as well, because it depends
on having proper CR0::TS setup. We'll fix this in the next patch.

Reviewed-by: Borislav Petkov <bp@alien8.de>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>