Documentation: Fix duplicate statement about raw_spinlock_t type

Unless it was duplicate on purpose, to emphasize that a raw_spinlock_t
is always a spinning lock regardless of PREEMPT_RT or kernel config,
it's a bit odd that this text is duplicate. So, this patch just clean
it up, keeping the consistency with the other sections of the text.

Cc: Thomas Gleixner <tglx@linutronix.de>
Fixes: 919e9e63 ("Documentation: Add lock ordering and nesting documentation")
Signed-off-by: NGuilherme G. Piccoli <gpiccoli@igalia.com>
Link: https://lore.kernel.org/r/20220321144133.49804-1-gpiccoli@igalia.comSigned-off-by: NJonathan Corbet <corbet@lwn.net>

Documentation/locking/locktypes.rst

@@ -211,9 +211,6 @@ raw_spinlock_t and spinlock_t
 raw_spinlock_t
 --------------
 
-raw_spinlock_t is a strict spinning lock implementation regardless of the
-kernel configuration including PREEMPT_RT enabled kernels.
-
 raw_spinlock_t is a strict spinning lock implementation in all kernels,
 including PREEMPT_RT kernels.  Use raw_spinlock_t only in real critical
 core code, low-level interrupt handling and places where disabling