soc: mediatek: pwrap: fix compiler errors

When compiling using sparse, we got the following error:
drivers/soc/mediatek/mtk-pmic-wrap.c:686:25: error: dubious one-bit signed bitfield

Changing the data type to unsigned fixes this.
Signed-off-by: Matthias Brugger <matthias.bgg@gmail.com>

drivers/soc/mediatek/mtk-pmic-wrap.c

@@ -683,7 +683,7 @@ struct pmic_wrapper_type {
 	u32 int_en_all;
 	u32 spi_w;
 	u32 wdt_src;
-	int has_bridge:1;
+	unsigned int has_bridge:1;
 	int (*init_reg_clock)(struct pmic_wrapper *wrp);
 	int (*init_soc_specific)(struct pmic_wrapper *wrp);
 };