x86: spinlock_32/64 substitute types and instructions

Use _slock_t for the spinlock data types and replace the instructions
by string defines, which makes the code of 32/64 bit versions more
or less identical.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>