[PATCH] i386: avoid redundant preempt_disable in __unlazy_fpu

There are two callers of __unlazy_fpu, unlazy_fpu and __switch_to, and
none of them appear to require additional preempt_disable/enable here.
Let's open-code save_init_fpu in __unlazy_fpu to save a few ops.

Signed-off-by: Jan Kiszka <jan.kiszka@web.de>
Signed-off-by: Andi Kleen <ak@suse.de>