scripts/kernel-doc: handle function pointer prototypes

There are some function pointer prototypes inside the net
includes, like this one:

	int (*pcs_config)(struct phylink_config *config, unsigned int mode,
			  phy_interface_t interface, const unsigned long *advertising);

There's nothing wrong using it with kernel-doc, but we need to
add a rule for it to parse such kind of prototype.
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Link: https://lore.kernel.org/r/fec520dd731a273013ae06b7653a19c7d15b9562.1592895969.git.mchehab+huawei@kernel.orgSigned-off-by: Jonathan Corbet <corbet@lwn.net>

scripts/kernel-doc

@@ -1771,6 +1771,11 @@ sub process_proto_function($$) {
 	$prototype =~ s@/\*.*?\*/@@gos;	# strip comments.
 	$prototype =~ s@[\r\n]+@ @gos; # strip newlines/cr's.
 	$prototype =~ s@^\s+@@gos; # strip leading spaces
+
+	 # Handle prototypes for function pointers like:
+	 # int (*pcs_config)(struct foo)
+	$prototype =~ s@^(\S+\s+)\(\s*\*(\S+)\)@$1$2@gos;
+
 	if ($prototype =~ /SYSCALL_DEFINE/) {
 		syscall_munge();
 	}