drm/nouveau/bios: fix DCB v1.5 parsing

memcmp->nv_strncmp conversion, in addition to name change, should have
inverted the return value.

But nv_strncmp does not act like strncmp - it does not check for string
terminator, returns true/false instead of -1/0/1 and has different
parameters order.

Let's rename it to nv_memcmp and let it act like memcmp.

Signed-off-by: Marcin Slusarz <marcin.slusarz@gmail.com>
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>

drivers/gpu/drm/nouveau/core/include/core/object.h

@@ -175,14 +175,18 @@ nv_mo32(void *obj, u32 addr, u32 mask, u32 data)
 	return temp;
 }
 
-static inline bool
-nv_strncmp(void *obj, u32 addr, u32 len, const char *str)
+static inline int
+nv_memcmp(void *obj, u32 addr, const char *str, u32 len)
 {
+	unsigned char c1, c2;
+
 	while (len--) {
-		if (nv_ro08(obj, addr++) != *(str++))
-			return false;
+		c1 = nv_ro08(obj, addr++);
+		c2 = *(str++);
+		if (c1 != c2)
+			return c1 - c2;
 	}
-	return true;
+	return 0;
 }
 
 #endif

drivers/gpu/drm/nouveau/core/subdev/bios/dcb.c

@@ -64,7 +64,7 @@ dcb_table(struct nouveau_bios *bios, u8 *ver, u8 *hdr, u8 *cnt, u8 *len)
 		}
 	} else
 	if (*ver >= 0x15) {
-		if (!nv_strncmp(bios, dcb - 7, 7, "DEV_REC")) {
+		if (!nv_memcmp(bios, dcb - 7, "DEV_REC", 7)) {
 			u16 i2c = nv_ro16(bios, dcb + 2);
 			*hdr = 4;
 			*cnt = (i2c - dcb) / 10;