HID: fix sparse warnings

Fix these sparse warnings:
.../hid/hid-core.c:100:15: warning: incorrect type in assignment (different signedness)
.../hid/hid-core.c:100:15: expected signed int [usertype] *value
.../hid/hid-core.c:100:15: got unsigned int *<noident>
by unsigned -> s32

.../hid/hid-input-quirks.c:336:10: warning: Using plain integer as NULL pointer
by 0 -> NULL

.../hid/usbhid/hid-core.c:786:46: warning: incorrect type in argument 3 (different signedness)
.../hid/usbhid/hid-core.c:786:46: expected int *max
.../hid/usbhid/hid-core.c:786:46: got unsigned int *<noident>
.../hid/usbhid/hid-core.c:787:47: warning: incorrect type in argument 3 (different signedness)
.../hid/usbhid/hid-core.c:787:47: expected int *max
.../hid/usbhid/hid-core.c:787:47: got unsigned int *<noident>
.../hid/usbhid/hid-core.c:788:48: warning: incorrect type in argument 3 (different signedness)
.../hid/usbhid/hid-core.c:788:48: expected int *max
.../hid/usbhid/hid-core.c:788:48: got unsigned int *<noident>
by int -> unsigned int

Signed-off-by: Jiri Slaby <[e-mail]>
Signed-off-by: Jiri Kosina <[e-mail]>

drivers/hid/hid-core.c

···
 	field->index = report->maxfield++;
 	report->field[field->index] = field;
 	field->usage = (struct hid_usage *)(field + 1);
-	field->value = (unsigned *)(field->usage + usages);
+	field->value = (s32 *)(field->usage + usages);
 	field->report = report;
 
 	return field;

drivers/hid/hid-input-quirks.c

···
 
 	{ VENDOR_ID_SUNPLUS, DEVICE_ID_SUNPLUS_WDESKTOP, quirk_sunplus_wdesktop },
 
-	{ 0, 0, 0 }
+	{ 0, 0, NULL }
 };
 
 int hidinput_mapping_quirks(struct hid_usage *usage, 

drivers/hid/usbhid/hid-core.c

···
 /*
  * Traverse the supplied list of reports and find the longest
  */
-static void hid_find_max_report(struct hid_device *hid, unsigned int type, int *max)
+static void hid_find_max_report(struct hid_device *hid, unsigned int type,
+		unsigned int *max)
 {
 	struct hid_report *report;
-	int size;
+	unsigned int size;
 
 	list_for_each_entry(report, &hid->report_enum[type].report_list, list) {
 		size = ((report->size - 1) >> 3) + 1;
···
 	struct hid_descriptor *hdesc;
 	struct hid_device *hid;
 	u32 quirks = 0;
-	unsigned rsize = 0;
+	unsigned int insize = 0, rsize = 0;
 	char *rdesc;
-	int n, len, insize = 0;
+	int n, len;
 	struct usbhid_device *usbhid;
 
 	quirks = usbhid_lookup_quirk(le16_to_cpu(dev->descriptor.idVendor),