scripts/kernel-doc: fix handling of parameters with parenthesis

lib/crc32c defines one parameter as:
	const u32 (*tab)[256]

Better handle parenthesis, to avoid those warnings:

./lib/crc32.c:149: warning: No description found for parameter 'tab)[256]'
./lib/crc32.c:149: warning: Excess function parameter 'tab' description in 'crc32_le_generic'
./lib/crc32.c:294: warning: No description found for parameter 'tab)[256]'
./lib/crc32.c:294: warning: Excess function parameter 'tab' description in 'crc32_be_generic'

Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>