config: simplify INLINE_SPIN_UNLOCK

From: Raghavendra K T <raghavendra.kt@linux.vnet.ibm.com>

Patch simplifies current INLINE_SPIN_UNLOCK. compile tested on x86_64

Change log:
get rid of INLINE_SPIN_UNLOCK entirely replacing it with UNINLINE_SPIN_UNLOCK
instead with the reverse meaning.

whover wants to uninline the spinlocks (like spinlock debugging, paravirt etc
all just do select UNINLINE_SPIN_UNLOCK

Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Raghavendra K T <raghavendra.kt@linux.vnet.ibm.com>