can: tcan4x5x: tcan4x5x_regmap_write(): remove not needed casts and replace 4 by sizeof

This patch simplifies the tcan4x5x_regmap_write(0 function by removing not
needed casts and replaces hardcoded "4" by appropriate sizeof()s.
Reviewed-by: NDan Murphy <dmurphy@ti.com>
Tested-by: NSean Nyekjaer <sean@geanix.com>
Link: https://lore.kernel.org/r/20201215231746.1132907-10-mkl@pengutronix.deSigned-off-by: NMarc Kleine-Budde <mkl@pengutronix.de>

drivers/net/can/m_can/tcan4x5x-regmap.c

@@ -38,10 +38,9 @@ static int tcan4x5x_regmap_gather_write(void *context, const void *reg,
 
 static int tcan4x5x_regmap_write(void *context, const void *data, size_t count)
 {
-	u16 *reg = (u16 *)(data);
-	const u32 *val = data + 4;
-
-	return tcan4x5x_regmap_gather_write(context, reg, 4, val, count - 4);
+	return tcan4x5x_regmap_gather_write(context, data, sizeof(u32),
+					    data + sizeof(u32),
+					    count - sizeof(u32));
 }
 
 static int tcan4x5x_regmap_read(void *context,