can: mcp25xxfd: mcp25xxfd_irq(): add missing initialization of variable set_normal mode

This patch fixes the following warning:

    drivers/net/can/spi/mcp25xxfd/mcp25xxfd-core.c:2155 mcp25xxfd_irq()
    error: uninitialized symbol 'set_normal_mode'.

by adding the missing initialization.
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Fixes: 55e5b97f ("can: mcp25xxfd: add driver for Microchip MCP25xxFD SPI CAN")
Link: https://lore.kernel.org/r/20200923114726.2704426-1-mkl@pengutronix.deSigned-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

drivers/net/can/spi/mcp25xxfd/mcp25xxfd-core.c

@@ -2080,7 +2080,7 @@ static irqreturn_t mcp25xxfd_irq(int irq, void *dev_id)
 
 	do {
 		u32 intf_pending, intf_pending_clearable;
-		bool set_normal_mode;
+		bool set_normal_mode = false;
 
 		err = regmap_bulk_read(priv->map_reg, MCP25XXFD_REG_INT,
 				       &priv->regs_status,