s390/debug: fix kernel-doc warnings

Fix kernel-doc warning due to incorrect parameter name in
kernel-doc function notation:

../arch/s390/include/asm/debug.h:484: warning: Function parameter or member 'pages' not described in 'DEFINE_STATIC_DEBUG_INFO'
../arch/s390/include/asm/debug.h:484: warning: Excess function parameter 'pages_per_area' description in 'DEFINE_STATIC_DEBUG_INFO'

Fixes: d72541f9 ("s390/debug: add early tracing support")
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: linux-s390@vger.kernel.org
Cc: Peter Oberparleiter <oberpar@linux.ibm.com>
Link: https://lore.kernel.org/r/20211005051657.16714-1-rdunlap@infradead.org


Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>