x86/fpu: Rename i387.h to fpu/api.h

We already have fpu/types.h, move i387.h to fpu/api.h.

The file name has become a misnomer anyway: it offers generic FPU APIs,
but is not limited to i387 functionality.

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>

arch/x86/kernel/fpu/xsave.c

@@ -9,7 +9,7 @@
 #include <linux/bootmem.h>
 #include <linux/compat.h>
 #include <linux/cpu.h>
-#include <asm/i387.h>
+#include <asm/fpu/api.h>
 #include <asm/fpu-internal.h>
 #include <asm/sigframe.h>
 #include <asm/tlbflush.h>